Analysis of ITER Materials and Technologies · 2016. 12. 8. · Energetic particles and collective phenomena 2 Chair: H. Berk 13.30-14.10 I-7: A. Biancalani Non-perturbative nonlinear

1

14th IAEA Technical Meeting on

Energetic Particles in Magnetic Confinement

Systems

1st - 4th September, 2015

IAEA Headquarters, Vienna International Centre

Vienna, Austria

Venue: M Building, Board Room A

IAEA Scientific Secretary

R. Kamendje

International Atomic Energy

Agency

Vienna International Centre

Wagramer Straße 5

PO Box 100

A-1400 Vienna, Austria

NAPC Physics Section

Tel: +43-1-2600-21707

Fax: +43-1-26007

E-mail: [email protected]

International Programme Advisory Committee

Chair: S. Pinches (ITER)

H. Berk (USA) , C. Hellesen (Sweden), A. Fasoli (Switzerland), Ph. Lauber

(Germany), W. Heidbrink (USA), S. Sharapov (UK), G.Vlad (Italy),

K. Shinohara (Japan), M.Osakabe (Japan), E. Frederickson (USA), X. Ding

(China)

Local Organisation Committee

Secretariat: L. Hedervari

Contact E-mail address: [email protected]

Meeting Website: http://www-naweb.iaea.org/napc/physics/meetings/

TM49508.html

Second Joint ITER-IAEA Technical Meeting

Analysis of ITER Materials and Technologies

11-13 December 2012

The Gateway Hotel Ummed Ahmedabad

Ahmedabad, India

mailto:[email protected]


http://www-naweb.iaea.org/napc/physics/meetings/%0bTM49508.html

http://www-naweb.iaea.org/napc/physics/meetings/%0bTM49508.html

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Topics

I. Alpha Particles Physics

II. Transport of Energetic Particles

III. Effects of Energetic Particles in Magnetic

Confinement Fusion Devices

IV. Collective Phenomena: Alfvén Eigenmodes,

Energetic Particle modes and Others.

V. Runaway Electrons and Disruption

VI. Diagnostics for Energetic Particles

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Schedule

Invited Orals (I) are allotted 30 min + 10 min for discussion.

Regular Orals (O) are allotted 20 min + 5 min for discussion.

Tuesday, 1st September

9.00-9.10 Opening Remarks

R. Kamendje

Session 1 Transport of energetic Particles I | Chair: S. Pinches

9.10-09.50

I-1: P. Schneider

Overview of diagnostic enhancements and physics studies of confined fast-ions in

ASDEX Upgrade

09.50-10:15 O-1: M. Podesta

Effects of fast ion phase space modifications by instabilities on fast ion modeling

10.15-10.45

Coffee Break (Photo)

Session 2

Transport of Energetic Particles II |

Chair: Y. Kolesnichenko

10.45-11.25 I-2: I. Furno

Non-diffusive transport of suprathermal ions in toroidally magnetized plasmas

11.25-11.50 O-2: C. Hopf

Recent progress in neutral beam current drive experiments on ASDEX Upgrade

11.50-12.15 O-3: R. Waltz

Development and validation of a critical gradient energetic particle driven Alfven

eigenmode transport model for DIII-D tilted neutral beam experiments

12.15-13.45

Lunch Break

Session 3 Transport of energetic Particles III | Chair: A. Fasoli

13.45-14.25 I-3: W. Heidbrink

Experimental determination of the threshold for “stiff” fast-ion transport by

Alfven eigenmodes

14.25-14.50 O-4: C.Collins

Measurements of Alfven eigenmode induced fast-ion transport in DIII-D

14.50-15.15 O-5: J. Rasmussen

Investigating fast-ion transport due to sawtooth crashes using Collective

Thomson Scattering

4

15.15-15.45 Coffee Break

Session 4

Transport of energetic Particles IV |

Chair: K.Shinohara

15.45-16.25 I-4: D. Pfefferle

Alpha particle confinement in the European DEMO

16.25-16.50 O-6: N. Gorelenkov

Validating predictive models for fast ion profile relaxation in burning plasmas

16.50-17.15

O-7: N. Bolte

Measurement and Simulation of Deuterium Balmer-Alpha Emission from First-

Orbit Fast Ions and the Application to General Fast-Ion Loss Detection in the

DIII-D Tokamak

17.15 Adjourn

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Wednesday, 2nd September

Session 5 Energetic particles in magnetic confinement fusion

devices | Chair: M. Hole

8.30-9.10 I-5: M. Schneider

Modelling 3rd harmonic Ion Cyclotron acceleration of D beam for JET

Fusion Product Studies

9.10-9.35 O-8: M. Schneller

Nonlinear Energetic Particle Transport in the Presence of Multiple Alfvenic

Waves in ITER

9.35-10.00 O-9: J. Kim

Experimental Observations of Fast-ion Losses on KSTAR


Session 6 Energetic particles and collective phenomena 1

Chair: Y. Todo

10.30-11.10 I-6: G. Fu

Stability and Nonlinear Dynamics of Beam-driven Instabilities in NSTX

11.10-11.35 O-10: M. Hole

The impact of anisotropy and flow on magnetic configuration, and stability

11.35-12.00 O-11: P. Rodrigues

Sensitivity of alpha-particle–driven Alfven eigenmodes to q-profile variation

in ITER scenarios

12.00-13.30 Lunch Break

Session 7 Energetic particles and collective phenomena 2

Chair: H. Berk

13.30-14.10 I-7: A. Biancalani

Non-perturbative nonlinear interplay of Alfven modes and energetic ions

14.10-14.35 O-12: F. Nabais

Observation of chirping modes in JET at frequencies above the Alfven

frequency


15.05-17.15 Poster Session 1

17.15 Adjourn

19.00 Meeting Dinner

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Thursday, 3rd September

Session 8 Energetic particles and collective phenomena III

Chair: C. Hellesen

8.30-9.10 I-8: Y. Kazakov

Fast Ion Generation with Novel Three-Ion ICRF Scenarios: from JET, W7-X

and ITER applications to aneutronic fusion studies

9.10-9.35 O-13: L. Horváth

Experimental investigation of the radial structure of energetic particle driven

modes

9.35-10.00 O-14: W. Zhang

Verification and Validation of Gyrokinetic Particle Simulation of Fast

Electron Driven beta-induced Alfven Eigenmode on HL-2A Tokamak


Session 9 Collective phenomena: Alfvén eigenmodes, energetic

particle modes and others I Chair: S. Sharapov

10.30-11.10 I-9: X. Wang

Structure of wave-particle interactions in nonlinear Alfvenic fluctuation

dynamics

11.10-11.35 O-15: S. Tripathi

Excitation of waves by a spiraling ion beam in a large magnetized plasma

11.35-12.00 O-16: D. Spong

Analysis of energetic particle driven Alfven instabilities in 3D toroidal

systems using a global gyrokinetic



particle modes and others II Chair: W. Heidbrink

13.30-14.10 I-10: A. Bierwage

Alfven Acoustic Channel for Ion Energy in High-Beta Tokamak Plasmas

14.10-14.35 O-17: M. Garcia-Munoz

Impact of localized ECRH on NBI and ICRH driven Alfven eigenmodes in the

ASDEX Upgrade tokamak


15.05-17.15 Poster Session 2

17.15 Adjourn

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Friday, 4th September


particle modes and others III | Chair: G. Vlad

8.55-9.35 I-11: M. Fitzgerald

Predictive nonlinear studies of TAE-induced alpha-particle transport in the

Q=10 ITER baseline scenario

9.35-10.00 O-18: A. Melnikov The study of NBI-driven chirping mode properties and radial location by

Heavy Ion Beam Probe in the TJII stellarator



particle modes and others IV | Chair: Ph. Lauber

10.30-11.10 I-12: M. Cole

Progress in non-linear electromagnetic gyrokinetic simulations of Toroidal

Alfven Eigenmodes

11.10-11.35 O-19: Y. Todo

Simulation study of profile stiffness of fast ions interacting with multiple

Alfven eigenmodes

11.35-12.00 O-20: M. Van Zeeland

Impact of Localized Electron Cyclotron Heating on Alfven Eigenmodes in

DIII-D


Session 13 Collective phenomena and runaway electrons |

Chair: M. Porkolab

13.30-13.55 O-21: G. Papp

Coupled kinetic-fluid simulation of runaway electron dynamics

13.55-14.20 O-22: Z. Chen

Study of disruption generated runaway electrons on J-TEXT tokamak


Session 14 Summaries | Chair: S. Pinches

14.50-15.20 S-1: H. Berk

Summary of theory presentations

15.20-15.20 S-2: M. Garcia-Munoz

Summary of experimental presentations

15.50-16.00 R. Kamendje

Closing Remarks

16.00 End of Meeting

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List of Invited Orals:

I-1 P. Schneider Overview of diagnostic enhancements and physics studies

of confined fast-ions in ASDEX Upgrade

I-2 I. Furno Non-diffusive transport of suprathermal ions in toroidally

magnetized plasmas

I-3 W. Heidbrink Experimental determination of the threshold for “stiff”

fast-ion transport by Alfven eigenmodes

I-4 D. Pfefferle Alpha particle confinement in the European DEMO

I-5 M. Schneider M Schneider, Modelling 3rd harmonic Ion Cyclotron

acceleration of D beam for JET Fusion Product Studies

I-6 G. Fu Stability and Nonlinear Dynamics of Beam-driven

Instabilities in NSTX

I-7 A. Biancalani Non-perturbative nonlinear interplay of Alfven modes and

energetic ions

I-8 Y. Kazakov Fast Ion Generation with Novel Three- Ion ICFR

Scenarios: from JET, W7-X an ITER applications to

aneutronic fusion studies.

I-9 X. Wang Structure of wave-particle interactions in nonlinear

Alfvenic fluctuation dynamics

I-10 A. Bierwage Alfven Acoustic Channel for Ion Energy in High-Beta

Tokamak Plasmas

I-11 M Fitzgerald Predictive nonlinear studies of TAE-induced alpha-

particle transport in the Q=10 ITER baseline scenario

I-12 M. Cole Progress in non-linear electromagnetic gyrokinetic

simulations of Toroidal Alfven Eigenmodes

9

I-1: overview of diagnostic enhancements and physics studies of

confined fast-ions in asdex upgrade

P. A. Schneider1,*

, B. Geiger1, S. K. Nielsen

2, G. Tardini

1, M. Weiland

1, S. Äkäslompolo

3,

A. S. Jacobsen2, F. Ryter

1, M. Salewski

2, the ASDEX Upgrade Team

1

and the EUROfusion MST1 Team4

1Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany

2Technical University of Denmark, Department of Physics, Dk-2800 Kgs. Lyngby, Denmark

3Aalto University, Finland

4http://www.euro-fusionscipub.org/mst1

*[email protected],

At the ASDEX Upgrade (AUG) tokamak the capabilities to diagnose confined fast particles were

successively enhanced over the past years. These include the collective Thomson scattering (CTS), the

fast-ion D-alpha (FIDA) diagnostic, the neutral particle analysers (NPA) and the neutron spectrometer.

The CTS was upgraded with an additional receiver for continuous background measurements. To extend

the coverage of the fast-ion velocity space, the FIDA diagnostic was upgraded from 3 to 5 optical arrays.

Red- and blueshifted parts of the FIDA radiation are measured simultaneously with a new spectrometer

setup. While FIDA and CTS have a good radial resolution, the measured signal is integrated over a range

in energy and pitch. Direct energy and pitch resolved measurements of the central fast-ion content are

obtained with a new active NPA. This NPA uses a compact solid state detector and is focused on the

same heating beam as the FIDA diagnostic for the active signal. To investigate fast edge localised

phenomena, the data acquisition system of the passive E,B-NPAs was upgraded. A neutron spectrometer

measures the neutron energy distribution resulting from D-D fusion reactions, thus providing an

independent diagnostic tool. The standard tool to interpret FIDA and NPA measurements is a parallel

version of the FIDASIM code. The run time for simulations of all channels is below 30 min for one time

point. An overview of recent results obtained with the improved set of diagnostics will be presented. The

measured impact of MHD instabilities such as ELMs and sawteeth on fast-ion confinement will be

discussed. The measured fast-ion redistribution due to sawteeth matches predictions based on the

Kadomtsev model very well. Information on the 2D fast-ion velocity space is obtained with tomographic

reconstructions using multiple FIDA views. The acceleration of neutral beam injected deuterons by the

2nd harmonic ICRF heating was confirmed with all fast-ion diagnostics and can be modeled using an RF

kick operator in TORIC or TRANSP. The radial fast-ion transport is investigated for on- and off-axis

heating and the measurements are compared with different transport models. Neoclassical transport can

be sufficient to explain the measurements in some cases, but when an anomalous contribution to the fast-

ion diffusivity is required to better match the observations, its value is typically below 1 m2/s.

10

I-2: non-diffusive transport of suprathermal ions in toroidally

magnetized plasmas

I. Furno, A. Bovet, A. Fasoli, K. Gustafson and P. Ricci

Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des

Plasmas, CH-1015 Lausanne, Switzerland

The interaction between small scale turbulence and suprathermal ions is still an open question for

burning plasmas in next generation fusion devices, such as in DEMO, in which suprathermal ions will be

injected by ICRH, NBI and generated by fusion reactions. As suprathermal ions will be responsible for a

large fraction of plasma heating and non-inductive current drive, understanding turbulent transport across

the magnetic field is of fundamental importance. Experimental data are required to compare and validate

the relevant theoretical and numerical models. In this contributions, we report on recent experimental,

numerical and theoretical studies in the laboratory device TORPEX, which permits full characterization

of suprathermal ion transport and turbulent structures.

TORPEX is a simple magnetized toroidal device in which, similarly to the Scrape-Off Layer of fusion

devices, field-aligned blobs are intermittently generated and propagate across the confining magnetic.

Suprathermal ions are injected in turbulent TORPEX plasmas using a miniaturized source and detected

using gridded-energy analyzers. Combining uniquely resolved three-dimensional measurements and

first-principle numerical simulations, we present first unambiguous evidence for sub-diffusive and super-

diffusive suprathermal ion transport regimes. We show that the transport character is determined by the

interaction of the suprathermal ion orbits with intermittent blobs, and is strongly affected by the ratio of

the suprathermal ion energy to the background plasma temperature. These results confirm the importance

of orbit gyroavering in mitigating the suprathermal ion turbulent transport.

Using conditional sampling we obtain time-resolved measurements of the cross-field dynamics of the

suprathermal ions, for the first time. Suprathermal ions interacting with radially propagating blobs

experience super-diffusive transport, which is associated with intermittent displacement events of the ion

beam.

This work was supported in part by the Fonds National Suisse de la Recherche Scientifique.

11

I-3: experimental determination of the threshold for “stiff”

fast-ion transport by alfvén eigenmodes

W. W. Heidbrink1, C.S. Collins

1, D.C. Pace

2, C.C. Petty

2,

L. Stagner1, M.A. Van Zeeland

2, Y.B. Zhu

1

1University of California Irvine, Irvine, CA, USA

2General Atomics, San Diego, CA, USA

Three separate DIII-D experiments suggest critical threshold-like behavior for fast-ion transport

in the presence of many, small-amplitude Alfvén eigenmodes (AE). During the current ramp,

although the amplitude of AE activity is largest for peaked beam deposition profiles, the

measured fast-ion profile is nearly identical [1]. Similarly, in steady-state scenario plasmas, fast-

ion transport is large in plasmas with many AEs but nearly classical in plasmas with few AEs

[2,3]. Recent experiments concentrate on accurate determination of the threshold for

appreciable transport. Modulation of one beam source

permits measurement of the incremental fast-ion transport

vs. AE amplitude. The AE amplitude is varied by

scanning the average beam and electron cyclotron heating

power. Neutral-particle analyzer (Fig. 1), fast-ion Dα

(FIDA), neutron, and scintillator loss detector diagnostics

all detect a rise in transport above a certain phase-space

dependent AE amplitude threshold. The FIDA data

indicate that the peak of the modulated fast-ion flux

occurs at normalized minor radii of ρ=0.3-0.6,

corresponding to the radial location of AEs.

These experiments are guiding development of “critical gradient” models that can predict alpha

profiles in future devices. The threshold for appreciable transport is one key issue. The data

show that a threshold based on marginal AE stability is too pessimistic. Initial analysis [3]

suggests that the onset of stochasticity due to island overlap is necessary. Another hypothesis

under investigation is that stiff critical gradient transport results only when the AE growth rate

exceeds the ion temperature gradient mode rate at the same low toroidal mode number.

References

[1] Heidbrink W.W. et al, Nucl. Fusion 53, 093006 (2013).

[2] Heidbrink W.W. et al, Plasma Phys. Control. Fusion 56, 095030 (2014).

[3] Holcomb C.T. et al, Phys. Plasmas (2015), submitted.

Fig.1. As the average injected beam power

increases, the amplitude of AE activity

increases until, above a threshold, the

modulated fast-ion flux suddenly increases.

12

I-4 alpha particle confinement in the european demo

D. Pfefferlé, H. W. Patten, S. Lanthaler, W. A. Cooper, J. P. Graves, and

A. Fasoli

École Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas

(CRPP), CH-1015 Lausanne, Switzerland

Energetic ions arise in fusion plasmas from heating systems such as ICRH, NBI and fusion reactions.

Their transport can be significantly enhanced in the presence of non-axisymmetric deformations and

3D internal structures, for example due to magnetic field ripple, external perturbations or MHD

activity. Energetic ions, by drifting away from field-lines, are more affected by non-axisymmetric

components than thermal particles; non conservation of toroidal momentum and large drift orbits leads to

enhanced collisionless losses. The VENUS-LEVIS orbit solver is designed to investigate supra-thermal

particle transport in the presence of general 3D fields. The code combines flexibility in the choice of

coordinate system with a strict Hamiltonian formulation of second-order guiding-centre and full-orbit

equations, switching between the two in the event of strong field variation (gradient, curvature and

torsion). Second-order terms, such as the Baňos drift, are important to reproduce matching particle and

guiding-centre trajectories. Confinement of alpha particles in the European DEMO reference design is

assessed, focusing on the effect of magnetic ripple caused by the finite number of toroidal coils. 3D

MHD equilibria, with nested ux-surfaces and a single magnetic axis, are computed within the VMEC

code. These nonlinear solutions to the MHD force balance, obtained via the Kruskal-Kulsrud energy

minimisation principle, conveniently describe tokamak saturated plasma states. This equilibrium

approach is compared with a perturbed vacuum field approach, where deviations from axisymmetry

are simply added to a 2D equilibrium and the plasma response is neglected.

13

I-5: modelling 3rd harmonic ion cyclotron acceleration of d beam

for jet fusion product studies experiments

M. Schneider1, T. Johnson

2, S. Sharapov

3, T. Hellsten

2, R. Dumont

1, M. Mantsinen

4,5,

M. Nocente6, J. Eriksson

7, V. Kiptily

3, J.-B. Girardo

1 and JET contributors*

EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, UK;1CEA, IRFM, F-13108 Saint-

Paul-lez-Durance, France; 2Ass. Euratom-VR, KTH, Stockholm, Sweden;

3CCFE, Culham Science Centre,

Abingdon, OX14 3D, UK; 4Catalan Institution for Research and Advanced Studies, Barcelona, Spain;

5Barcelona

Supercomp. Center, Barcelona, Spain ; 6Dipartimento di Fisica “G. Occhialini”, Università degli Studi di Milano-

Bicocca, Milano, Italy;7Dept. of Physics & Astronomy, Uppsala Univ., Sweden

Fusion products will play a crucial role in future tokamak fusion devices: alpha particles are mainly

aimed at sustaining fusion reactions and reach the ignition, while other fusion products are also used for

diagnostic purposes. For this reason it is essential to fully understand their behaviour in present day

tokamaks. To this prospect, 2014 JET fusion product studies experiments were based on ICRH 3rd

harmonic heating of D beams in order to generate a MeV range D tail to enhance D-D and D-He3 fusion

reactions and study confined and lost fusion products with dedicated diagnostics and modelling tools.

These experiments have demonstrated a clear production of fast ion D tail, visible from neutron [1] and

gamma-ray [2] diagnostics. Proper modelling is required to ensure the correct interpretation of these data

and to go beyond actual measurements by simulating the ion dynamics with time-evolving power

references.

SPOT [3] is an orbit following Monte Carlo code recently extended with the RFOF [4] library for

simulating the interaction between ions and ICRF waves in the context of the quasilinear theory. The

SPOT/RFOF package has been run in association with the EVE full wave code for ICRF heating [5], and

the NEMO beam deposition code [6] to simulate the relevant discharges including the NBI+ICRH

synergy.

A comparison of the ion distribution and high energy cut off between the SPOT/RFOF code and the

neutron and gamma-ray spectroscopy is presented, showing an overall good agreement. Diagnostic

sensitivity according to their line of sight is explored. PION [7] and SELFO-light [8] simulations are also

included for comparison. In addition, the fast D tail decay/sustainment when switching off NBI and

ICRF heating sources is presented. The ICRF heating efficiency according to the geometry of the beam

injecting Positive Ions Neutral Injectors (PINIs) is analysed. Finally, a sawtooth activity has been

observed in some discharges, which has been interpreted using SPOT/RFOF simulations in the

framework of Porcelli’s theoretical model: NBI+ICRH accelerated ions have a strong stabilizing effect,

yet sawtooth crashes occur, due in particular to tornado modes induced by fast ions [9].

[1] M. Gatu Johnson et al, Nuc. Instr. Meth. A 591 417 (2008)

[2] V. G. Kiptily, et al, NF 42, 999 (2002) [3] M. Schneider et al, PPCF 47, 2087 (2005)

[4] T. Johnson et al, AIP Proc. 1406, 373 (2011) [5] R. Dumont et al, NF 53, 013002 (2013)

[6] M. Schneider et al, NF 51, 063019 (2011) [7] L.-G. Eriksson et al, NF 33,1037 (1993)

[8] T. Hellsten et al, NF 53 093004 (2013) [9] J.-B. Girardo et al, to be submitted to PP.

* See the Appendix of F. Romanelli et al.,Proceedings of the 25th IAEA Fusion EnergyConference 2014, Saint

Petersburg, Russia 2.

14

I-6: stability and nonlinear dynamics of beam-driven

instabilities in nstx

G. Y. Fu1, F. Wang

1, D.Y. Liu

2, E. D. Fredrickson

1, M. Podesta

1

1Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA

2University of California, Irvine, California 92697, USA

Email Address of Submitting Author: [email protected]

Energetic particle modes and Alfvénic modes driven by super-Alfvénic beam ions were routinely

observed in neutral beam heated plasmas on the National Spherical Torus Experiment (NSTX). These

modes can significantly impact beam-ion transport, thus causing beam-ion redistribution and losses.

Recent simulation results with the kinetic/MHD hybrid code M3D-K show excitation and nonlinear

saturation of n=1 fishbone with strong frequency chirping and beam ion radial profile flattening [1]. The

simulation results of TAEs show mode radial structure consistent with the reflectometer measurements of

electron density fluctuations [2]. In this paper we report on new self-consistent simulations of both

fishbone instability and TAEs in NSTX plasmas. Our model is self-consistent with mode structure

determined non-perturbatively including effects of energetic particles and plasma toroidal rotation. First,

the stability of the n=1 fishbone is systematically calculated with effects of plasma toroidal rotation for

weakly reversed shear q profiles with minimum safety factor above unity. It is found that a new

instability region appears for qmin > 1.35 when rotation is included. The corresponding fishbone mode

structure has strong ballooning feature. In contrast, the fishbone with qmin < 1.35 has a dominant m/n=1/1

kink structure. Nonlinear simulation shows strong mode frequency chirping as beam ions are

redistributed. Second, NSTX experimental results show that multiple low-amplitude beam-driven TAEs

with weak frequency chirping can transit to mode avalanche with much larger amplitudes and strong

frequency chirping. In order to explore mechanisms of avalanche, M3D-K nonlinear simulations of

multiple beam-driven TAEs and the n=1 fishbone have been carried out for the first time. The simulation

results show strong interaction between TAEs and fishbone that either enhances or reduces saturation

level of individual modes depending on mode number and other parameters. As beam ion beta increases

beyond stability threshold, mode saturation levels are found to increases sharply. When beam ion beta

exceeds some critical value, the locally flattening regions merge together resulting in global particle

transport and substantial particle loss. These results are similar to the TAE avalanche observed in NSTX.

[1] F. Wang et al, Phys. Plasmas 20, 102506 (2013)

[2] D. Liu et al, Phys. Plasmas 22, 042509 (2015)

mailto:Email%20Address%20of%20Submitting%20Author:%[email protected]

15

I-7: “non-perturbative nonlinear interplay of alfvén modes and

energetic ions”.

A. Biancalani1, A. Bottino

1, Ph. W. Lauber

1, B. Scott

1, A. Mishchenko

2, A. Koenies

2,

C. Di Troia3, F. Zonca

3,4

1Max-Planck-Institut für Plasmaphysik, 85748 Garching, Germany.

2Max-Planck-Institut für Plasmaphysik, 17491 Greifswald, Germany.

3ENEA C. R. Frascati - C. P. 65-00044 Frascati, Italy.

4Institute for Fusion Theory and Simulation, Zhejiang University, 310027 Hangzhou, PRC.

Numerical simulation results of Alfvén modes driven unstable by supra-thermal ions in tokamaks are

presented. The global nonlinear gyrokinetic particle-in-cell code NEMORB is used for such studies. The

mode structure is analyzed in the linear and in the nonlinear phase; and, thereby, the self-consistent

(nonlinear) interplay of mode structure and energetic particle transport is systematically investigated and

explained. In particular, both wave-particle and wave-wave nonlinearities are considered and the regimes

where either one is dominant are identified by varying the linear instability drive. Various aspects of the

nonlinear dynamics are addressed separately, by artificially switching off other nonlinearities. Thus, also

the effect of nonlinear modification of the mode frequency is investigated. Finite-Larmor-radius effects

of energetic ions on mode structure, frequency and growth rate are also described. The insights into the

isolated nonlinear dynamics are then used to interpret results of fully non-perturbative nonlinear

simulations.

Acknowledgements:

This work has been carried out within the framework of the EUROfusion Consortium and has received

funding from the Euratom research and training programme 2014-2018 under grant agreement No

633053. The views and opinions expressed herein do not necessarily reflect those of the European

Commission. Simulations were performed on the IFERC-CSC Helios supercomputer within the

framework of the ORBFAST project. This work has been done in the framework of the nonlinear

energetic particle dynamics (NLED) European Enabling Research Project (EUROFUSION WP15-ER-

01/ENEA-03).

16

I-8: fast ion generation with novel three-ion icfr scenarios: from

jet, w7-x and iter applications to aneutronic fusion studies

Ye.O. Kazakov1, D. Van Eester

1, J. Ongena

1, R. Bilato

2, R. Dumont

3, E. Lerche

1, A. Messiaen

1

1 Laboratory for Plasma Physics, LPP-ERM/KMS, Brussels, Belgium

2 Max-Planck-Institut für Plasmaphysik, Garching, Germany

3 CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France


Plasma heating with waves in the ion cyclotron range of frequencies (ICRF) is widely used in fusion research. In

addition to plasma heating itself, ICRF has a number of important supplementary applications, including the

generation of high energy ions. This is typically needed for fusion product studies, when RF heating is applied to

accelerate a small group of resonant ions to very high energies [1]. Such particles mimic fusion-born alphas and this

provides a tool to study fast ion dynamics and to check and optimize the quality of plasma confinement. This is the

main function of the ICRF system in the Wendelstein 7-X project.

In present-day fusion devices, ICRF minority heating normally uses concentrations of resonant ions of about 5%,

resulting in tail energies of a few hundred keV. MeV-range particles are typically generated with a combination of

NBI and second or third harmonic ICRF heating [2]. Recently, we have identified a new set of ICRF scenarios,

which likewise minority heating rely on fundamental (N = 1) ion cyclotron absorption, and thus NBI pre-heating is

not such essential as for the harmonic ICRF scenarios. A distinct feature of the three-ion ICRF scenarios is the high

efficiency of RF power absorption at very low resonant ion concentrations (~ 1% and even below) [3]. This is

possible because of the improved wave polarization in the absorption region. As a result, the absorbed power per

resonant particle is much higher than for the traditional two-ion minority heating scenarios and resonant ions can be

accelerated to MeV energies with ICRF.

We review possible applications of the proposed method for the

generation of high energy ions in fusion plasmas. Three-ion

ICRF scenarios are particularly relevant for future fusion machines,

e.g. W7-X and ITER, where significantly higher plasma densities

will be used for operation. We also discuss the relevance of the

proposed heating scenarios for aneutronic fusion reaction studies

p + 11

B → 3α + 8.7 MeV. As follows from Fig. 1, a very efficient

absorption of ICRF power by a small fraction of boron ions is

possible in a hydrogen-tritium mixture H:T ≈85%:15% .This can be

used for the acceleration of boron ions to MeV energies, where the

cross-section of the proton-boron fusion reaction has a maximum.

[1] S.E. Sharapov et al., “Fast Ion D-D and D-3He Fusion on JET”, this conference.

[2] M.J. Mantsinen et al., “Analysis of ICRF heating and ICRF-driven fast ions in recent JET

experiments”, this conference.

[3] Ye.O. Kazakov, D. Van Eester, R. Dumont and J. Ongena, Nucl. Fusion 55 032001 (2015).

Fig.1. ICFR power absorption efficiency

by boron ions in T-hydrogen plasmas


17

I-9: structure of wave-particle interactions in nonlinear alfvénic

fluctuation dynamics*

X. Wang1, S. Briguglio

2, G. Fogaccia

2, Ph. Lauber

1, M. Schneller

1, G. Vlad

2, F. Zonca

2

1Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, Garching D-85748, Germany.

2ENEA for EUROfusion, Via E. Fermi 45, 00044 Frascati, Italy

Emai Address of Submitting Author: [email protected]

Recent theoretical [1, 2] and numerical simulation studies [3, 4] show that non-adiabatic frequency

chirping and phase locking of Alfvén waves lead to meso- and macro-scale transport of resonant

particles. The interplay between mode structure and resonant particles is crucial for understanding the

nonlinear dynamics of such waves excited by energetic particles (EP) in fusion plasmas. In our work,

these dynamics are investigated by means of the nonlinear hybrid magnetohydrodynamics gyrokinetic

code (XHMGC) [5, 6] with particular emphasis on beta induced Alfvén eigenmodes (BAE), which have

been observed in fusion experiments and can generate significant EP transport [7]. Nonlinear dynamics

are investigated, ranging from marginal stability to strongly driven regimes. Phase space zonal structures

(PSZS) [2] are analyzed using phase space numerical diagnostics based on the Hamiltonian mapping [4];

demonstrating that nonperturbative EP response and finite radial structures of fluctuations in nonuniform

plasmas become increasingly more important for increasing EP drive.

[1] F. Zonca et al., Plasmas Phys. Control. Fusion 57, 014024 (2015)

[2] F. Zonca et al., New J. Phys. 17, 013052 (2015)

[3] G. Vlad et al., Nucl. Fusion 53, 083008 (2013)

[4] S. Briguglio et al., Phy. Plasmas 21, 112301 (2014)

[5] S. Briguglio et al., Phys. Plasmas 2, 3711 (1995).

[6] X. Wang et al., Phys. Plasmas 18, 052504 (2011).

[7] Ph. Lauber et al., Plasmas Phys. Control. Fusion 51, 124009 (2009).

[8] Ph. Lauber et al., J. Comp. Phys., 226(1) 447 (2007)

This work has been carried out within the framework of the EUROfusion Consortium and has received

funding from the Euratom research and training programme 2014-2018 under grant agreement No.

633053. The views and opinions expressed herein do not necessarily reflect thoseof the European

Commission.


18

I-10: alfvén acoustic ahannel for ion energy in high - beta

tokamak plasmas

A. Bierwage 1, N. Aiba

1, K. Shinohara

2, M. Yagi

1

1 Japan Atomic Energy Agency, Rokkasho Fusion Institute, Aomori, Japan

2 Japan Atomic Energy Agency, Naka Fusion Institute, Ibaraki, Japan

The stable MHD response of a high-beta JT-60U plasma was analyzed numerically for the first time. On-

axis toroidal beta values up to β = 3.5% were considered, which is a regime relevant for burning plasmas.

The following results were obtained [1]:

1. Discrete MHD modes with dominant sound polarization are found in regions where the

sound wave continua have a weak radial dependence. We call these modes “global slow

magnetosonic eigenmodes” (GSME).

2. For β 1%, GSMEs overlap with continuous spectra of shear Alfvén waves and the two

branches couple. This gives rise to new discrete modes with mixed Alfvén and sound

polarization, which we call “beta-induced Alfvén continuum modes” (BACM).

3. When fast ions excite an energetic particle mode (EPM) [2] near the radius and

frequency where such Alfvén -acoustic wave coupling occurs, the EPM wave packet

is found to acquire features of a BACM.

The EPM simulations were carried out with the hybrid MHD-gyrokinetic code MEGA, which was

recently successfully validated against DIII-D and JT-60U experiments [3,4,5]. The EPMs in the JT-60U

scenario studied here were driven by tangentially injected negative-ion-based neutral beam (N-NB) ions

with a birth energy of about 400 keV. The above discoveries have several important implications. First,

they reveal a new noncollisional self-heating channel for burning plasmas:

Resonant Drive BACM Dissipative Heating

Fast ions Alfvén waves Sound waves Thermal bulk ions.

This finding motivates an intensification of research activity in the field of “alpha particle energy

channeling” [6,7] with the goal to quantify how much the new Alfvén acoustic channel enhances fusion

performance above previous estimates that were based on collisions with electrons only. Second, the

above wave energy channeling and associated wave damping has implications for fast ion confinement.

On the one hand, strong wave damping (strong self-heating, weak transport) is desirable at frequencies

where newly born alpha particles (3.5 MeV) resonate. On the other hand, strong transport is desirable at

mode frequencies where partially slowed down alpha particle “ash” (~100 keV) resonates.

[1] Bierwage et al., Phys. Rev. Lett. 114 (2015) 015002. [2] Chen, Phys. Plasmas 1 (1994) 1519. [3] Todo et al.,

Nucl. Fusion 54 (2014) 104012. [4] Todo et al., Proc. 25th IAEA FEC 2014 (St. Petersburg, Russia), IAEA, Vienna

(2015), invited TH/7-1. [5] Bierwage et al., Proc. 25th IAEA FEC 2014 (St. Petersburg, Russia), IAEA, Vienna

(2015), poster TH/P7-39. [6] Fish and Rax, Phys. Rev. Lett. 69 (1992) 612. [7] Fish, Trans. Fusion Sci. Tech. 51

(2007) 1.

19

I-11: predictive nonlinear studies of tae-induced alpha-particle

transport in the q=10 iter baseline scenario

M. Fitzgerald 1, S. E. Sharapov

1, P. Rodrigues

2, S. Pinches

3, D. Borba

2

1 CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom

2 Instituto de Plasmas e Fusão Nuclear, IST, Univ. de Lisboa, 1049-001 Lisboa, Portugal

3 ITER Organization, 13067 St Paul-lez-Durance Cedex, France


We use the HAGIS code [1] to compute the nonlinear stability of the Q=10 ITER baseline scenario [2] to

TAEs and the effects of these modes on fusion -particle redistribution. Our calculations build upon an

earlier linear stability survey [3] carried out using the MISHKA and CASTOR-K codes, which identifies

relevant TAEs and provides accurate values of bulk ion, impurity ion and electron thermal landau

damping for our HAGIS calculations, as well as a benchmark for our linear -particle drive calculations.

We also include analytical estimates for radiative damping. In linear calculations, it is found that even in

the presence of / ~ 1% thermal bulk damping of core localised modes, -particle drive of core

localised TAEs with toroidal mode numbers around n=29 can be as large as 3-5%, and thus linearly

unstable with large growth rates. Nonlinear calculations of 88 TAEs in the range n=15-35 and

subsequent effects on alpha particles have been performed. The effects of frequency sweeping were also

included to examine possible phase space hole and clump convective transport. We find that core

localised modes are dominant (expected from linear theory), and that linearly stable modes are

destabilized nonlinearly. When damping is neglected, the core localised modes reach a maximum

amplitude of 3104/ BBr , with global modes being smaller by an order of magnitude or more.

When damping is introduced, the maximum amplitude drops to 4103/ BBr (Fig. 1). Stochastic

transport occurs in a narrow region where the most unstable core localised modes are found (Fig 2),

implying the formation of a transport barrier at 5.0/ ar , where the weakly driven global modes are

found. We thus expect that for TAEs with n=15-35 in this scenario, -particle redistribution will be

confined to a small region and losses will be negligible. We are currently extending the study to include

TAEs with n=10-14, and will include modelling of these modes in the results presented at the

conference.

Figure 1. Amplitude growth and saturation of 88

TAEs including the effects of damping and

unlocked mode phases.

Figure 2. Poincare plots of test particle orbits in the presence of core localized

(red) and global (blue) TAEs.

This work has received funding from Euratom and the RCUK Energy Programme [grant number EP/I501045]. The

views and opinions expressed herein do not necessarily reflect those of the European Commission.[1] Pinches, S.

D. et al. (1998). Comput. Phys. Commun., 111, 133; [2] Polevoi, A. et al. (2002). J. Plasma Fusion Research,

SERIES, 5, 82; [3] P.Rodrigues et al. (2015) submitted to Nuclear Fusion


20

I-12: progress in non-linear electromagnetic gyrokinetic

simulations of toroidal alfvén eigenmodes

M. D. J. Cole1, A. Mishchenko

1, M. Borchardt

1, R. Hatzky

2, R. Kleiber

1, A. Könies

1

1 Max Planck Institute for Plasma Physics, Greifswald, Germany 2 Max Planck Institute for Plasma Physics, Garching, Germany


Gyrokinetic numerical simulation has been a successful tool for predicting the behaviour of magnetised

plasmas in fusion devices. Global modes, such as the Toroidal Alfvén Eigenmode (TAE), at finite β

require a global electromagnetic treatment. This is computationally demanding and can introduce

conceptual numerical complications. Since such modes pose a threat to the operation of a viable fusion

reactor, it is important to be able to predict and control their behaviour prior to the construction of such a

device. In this work, we present the results of non-linear investigations of fast-ion driven TAEs using

reduced models, which mitigate some of the numerical requirements. Furthermore, we describe the

progress of on-going work using a model in which all species are treated gyrokinetically.

21

list of regular orals:

O-1 M. Podesta Effects of fast ion phase space modifications by instabilities

on fast ion modelling

O-2 C. Hopf Recent progress in neutral beam current drive experiments

on ASDEX Upgrade

O-3 R. Waltz Development and validation of a critical gradient energetic

particle driven Alfven eigenmode transport model for DIII-

D tilted neutral beam experiments

O-4 C. Collins Measurements of Alfven eigenmode induced fast-ion

transport in DIII-D

O-5 J. Rasmussen Investigating fast-ion transport due to sawtooth crashes

using Collective Thomson Scattering

O-6 N. Gorelenkov Validating predictive models for fast ion profile relaxation

in burning plasmas

O-7 N. Bolte Measurement and Simulation of Deuterium Balmer-Alpha

Emission from First-Orbit Fast Ions and the Application to

General Fast-Ion Loss Detection in the DIII-D Tokamak

O-8 M. Schneller Nonlinear Energetic Particle Transport in the Presence of

Multiple Alfvénic Waves in ITER

O-9 J. Kim Experimental Observations of Fast-ion Losses on KSTAR

O-10 M. Hole The impact of anisotropy and flow on magnetic

configuration, and stability

O-11 P. Rodrigues Sensitivity of alpha-particle–driven Alfven eigenmodes to q-

profile variation in ITER scenarios

22

O-12 F. Nabais Observation of chirping modes in JET at frequencies above

the Alfven frequency

O-13 L. Horváth Experimental investigation of the radial structure of

energetic particle driven modes

O-14 W. Zhang Verification and Validation of Gyrokinetic Particle

Simulation of Fast Electron Driven beta-induced Alfven

Eigenmode on HL-2A Tokamak

O-15 S. Tripathi Excitation of waves by a spiraling ion beam in a large

magnetized plasma

O-16 D. Spong Analysis of energetic particle driven Alfven instabilities in

3D toroidal systems using a global gyrokinetic

O-17 M. Garcia-

Munoz

Impact of localized ECRH on NBI and ICRH driven Alfven

eigenmodes in the ASDEX Upgrade tokamak

O-18 A. Melnikov The study of NBI-driven chirping mode properties and

radial location by Heavy Ion Beam Probe in the TJII

stellarator

O-19 Y. Todo Simulation study of profile stiffness of fast ions interacting

with multiple Alfven eigenmodes

O-20 M. Van Zeeland Impact of Localized Electron Cyclotron Heating on Alfven

Eigenmodes in DIII-D

O-21 G. Papp Coupled kinetic-fluid simulation of runaway electron

dynamics

O-22 Z. Chen Study of disruption generated runaway electrons on J-TEXT

tokamak

23

O-1 effects of fast ion phase space modifications by instabilities

on fast ion modeling

M. Podestà, M. Gorelenkova, N. N. Gorelenkov, E. Fredrickson and R. B. White

Princeton Plasma Physics Laboratory, Princeton NJ - 08543, USA

Email Address of submitting Author: [email protected]

Reduced models for energetic particle (EP) transport are emerging as an effective tool for long time-scale

integrated simulations of tokamak plasmas, possibly including the effects of instabilities on EP

dynamics. Available models differ in how EP distribution properties are modified by instabilities, e.g. in

terms of gradients in real or phase space. It is therefore crucial to assess to what extent different

assumptions in the models affect predicted quantities such as EP profile, energy distribution, Neutral

Beam (NB) driven current and energy/momentum transfer to the thermal populations. A newly

developed kick model, which includes modifications of the EP distribution by instabilities in both real

and velocity space, is used to address these issues. The model condenses information on EP distribution

response to instabilities, e.g. modeled through the particle following code ORBIT, in a EP transport

probability. The latter can be included in the NUBEAM module of the TRANSP tokamak transport code,

which computes EP evolution. Coupled to TRANSP simulations, the kick model is used to study NB-

heated NSTX discharges featuring unstable toroidal Alfvén eigenmodes (TAEs). Results show that TAEs

selectively affect the EP energy distribution, with a decrement of 10-30% for the core NB driven current.

When TAEs evolve in so-called TAE avalanches, the model reproduces the measured drops of ~10% in

the neutron rate. Results from the kick model will be compared to those from a simple diffusive model

and a “critical gradient” model, which postulate radial EP gradient as the only transport drive. The

importance of EP modifications in real and velocity space is discussed in terms of accuracy of

simulations vs. experimental results, with emphasis on Neutral Beam current.

(Work supported by U.S. DOE Contract DE-AC02-09CH11466).


24

O-2: recent progress in neutral beam current drive experiments

on asdex upgrade

C. Hopf, D. Rittich, B. Geiger, A. Mlynek, M. Reich, A. Bock, A. Burckhart, C. Rapson, F. Ryter, the

ASDEX Upgrade Team and the EUROfusion MST1 Team*

Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany

*http://www.euro-fusionscipub.org/mst1

Past studies comparing neutral beam current drive with on- and off-axis beams at 5 MW gave

contradicting results. In the first experiments anomalous fast-ion transport was needed to understand the

current profiles constrained by MSE [1], but later similar experiments showed that the fast-ion density

profile constrained by fast-ion D (FIDA) spectroscopy could be modelled by neoclassical theory alone

[2]. It remained an open question whether this apparent contradiction pointed to a problem in NBCD

theory, or whether it could be attributed to differences between the two sets of experiments.

In 2014 a new effort was started to clarify this question. A modified heating scheme that uses a total of

7.5 MW NBI (three beams) while switching 5 MW between on- and off-axis beams allows for

continuous FIDA and MSE measurements [2]. ECCD is employed to avoid MHD instabilities and

feedback-controlled central ECRH keeps the Te profiles very constant between the on- and off-axis

phases. The predicted higher current drive efficiency of the tangential off-axis beams is confirmed by the

expected drop in the loop voltage. The on- and off-axis FIDA profiles qualitatively show the expected

differences, but quantitative simulation of the off-axis profiles requires the assumption of anomalous fast

ion diffusion localized at approximately half minor radius. MSE and the new Faraday rotation

polarimetry (“FRP”) diagnostic, that is also sensitive to changes of the q profile, reveal changes in the

driven current profile after switching from on- to off-axis NBI that are also in better agreement with the

assumption of some anomalous fast ion transport.

In the coming months our work will primarily focus on characterizing the conditions under which fast

beam-ion transport is or is not neo-classical as well as improved quantification of the overall driven

current in order to test NBCD theory. The experiments will also profit from the upgrades and

improvements of the existing MSE and FRP systems as well as a new imaging MSE system. The present

status of the ongoing studies will be reported.

[1] S. Günter et al., Nucl. Fusion 47 (2007) 920–928

[2] B. Geiger et al., Plasma Phys. Control. Fusion 57 (2015) 014018

25

O-3: development and validation of a critical gradient energetic

particle driven Alfven eigenmode transport model for diii-d

tilted neutral beam experiments

R. E. Waltz1, E.M. Bass

2, W.W. Heidbrink

3, and M.A. VanZeeland

1

1General Atomics, San Diego, CA

2University of California San Diego, San Diego, CA

3University of California Irvine, Irvine, CA

Recent experiments with the DIII-D tilted neutral beam injection (NBI), which significantly vary the

beam energetic particle (EP) source profiles, have provided strong evidence that unstable Alfven

eigenmodes (AE) drive stiff EP transport at a critical EP density gradient[1]. We hope to identify the

critical gradient with the condition that the maximum local AE growth rate falls to the local ITG/TEM

rate at the same low-n toroidal mode number. This condition was supported by early nonlinear local

GYRO simulations [2]. It is somewhat more optimistic than stiff EP transport at the AE marginal

stability gradient used in a recent ITER projection of AE driven alpha confinement losses[3]. The AE

and ITG/TEM growth rates are taken from GYRO with comparison of Maxwellian to slowing down

beam-like EP distribution with slightly lower critical gardient. The critical gradient condition is to be

verified by nonlinear GYRO simulations of the DIII-D NBI discharges with unstable low-n AE modes

embedded in high-n ITG/TEM turbulence. The ALPHA EP density transport code[3] combines the low-

n stiff EP critical density gradient AE transport at the mid core radii with the Angioni et al [4] energy

independent high-n ITG/TEM density transport model which controls the central core EP density profile.

For the on-axis NBI heated DIII-D shot 146102, while the net loss to the edge is small, about half the

birth fast ions are lost from the central core r/a < 0.5 and the central density is about half the slowing

down density. Results are in good agreement with the MHD equilibrium fit NBI fast ion pressure profile.

[1] Heidbrink W.W., Van Zeeland M.A., et. al. 2013 Nucl. Fusion 53, 093006.

[2] Bass E.M. and Waltz R.E. 2010 Phys. Plasmas 17, 112319.

[3] Waltz R.E. and Bass E.M. 2014 Nucl. Fusion 54, 104006.

[4] Angioni C. and. Peters A. G. 2008 Plasma Phys. 15 052307.

Acknowledgement: This work was supported by the U.S. Department of Energy under GA-Grant Nos. DE-FG02-

95ER54309, DE-FC02-08ER54977, and DE-FC02-04ER54698

26

O-4: measurements of alfvén eigenmode induced fast-ion

transport in diii-d

C.S. Collins1, W.W. Heidbrink

1, L. Stagner

1, C.C. Petty

2, D.C. Pace

2, M.A. Van Zeeland

2 ,Y.B. Zhu

1

1University of California at Irvine, Irvine, CA 92697, USA

2General Atomics, PO Box 85608, San Diego, CA 92186-5608, USA

Email Address of submitting Author: [email protected]

The onset threshold for fast-ion transport due to Alfvén eigenmode (AE) activity in DIII-D appears to

differ between various fast-ion diagnostics, indicating a phase-space dependence of fast-ion transport. A

method for measuring fast-ion transport using a source modulation technique will be discussed. In the

experiment, the AE activity is varied with total neutral beam injected power, while the fast-ion pressure

profile is modulated using an off-axis neutral beam. The neutral-particle analyzer (SSNPA) is sensitive to

the trapped particle population and indicates sudden onset of transport at 6 MW beam power, while the

neutron diagnostic, which is sensitive to the high-energy, counter-passing particles, exhibits threshold

near 4 MW. Fast-ion Dα (FIDA) spectroscopy indicates radially localized transport of the co-passing

population corresponding to the location of mid-core AEs. Transport is determined from the continuity

equation for fast-ions, where the time evolution of the measured fast-ion population depends on the

source (the modulated beam), the sink (fast-ion thermalization), and transport (due to resonant wave-

particle interactions with AEs). The analysis is more complicated than conventional transport analysis

techniques, since the measurement is a convolution of the fast-ion distribution function and the

instrument weight function which depends on fast-ion energy, pitch, and the diagnostic geometry. The

source can be calculated using TRANSP to find the classical fast-ion distribution function in the absence

of transport, and the FIDASIM code produces synthetic FIDA and SSNPA signals. At the lowest beam

power where transport is small, the modulated FIDA, SSNPA, and neutron signals closely match the

simulated signals. At large beam powers, the measured signals deviate substantially from the classical

simulations. Recent upgrades to the FIDA diagnostic enables comparison to an expanded phase-space,

with 11 oblique viewing chords spanning the full radius and 3 vertical viewing chords. Pinpointing the

onset of transport in phase-space and the scaling law for stiff transport beyond threshold is useful in

validating critical gradient models [1,2] that aim to predict alpha profiles, beam ion profiles, and losses in

future burning plasma devices.

Work supported by the US Department of Energy under SC-G903402, DE-FC02-04ER54698 & DE-AC02-

09CH11466.

References

[1] Heidbrink W.W. et al, Nucl. Fusion 53, 093006 (2013).

[2] Waltz, R.E. and Bass, E.M., Nucl. Fusion 54, 104006 (2014).


27

O-5: investigating fast-ion transport due to sawtooth crashes

using collective thomson scattering

J. Rasmussen1, S. K. Nielsen

1, M. Stejner

1, A. S. Jacobsen

1, S. B. Korsholm

1, F. Leipold

1, M. Salewski

1,

B. Geiger2, F. Ryter

2, M. Schubert

2, J. Stober

2, D. Wagner

2, the ASDEX Upgrade Team

2, the

EUROFusion MST1 Team3

1Technical University of Denmark, Department of Physics, DK-2800 Kgs. Lyngby, Denmark.

2Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, D-85748 Garching, Germany

3http://www.euro-fusionscipub.org/mst1


Sawtooth crashes redistribute heat, particles, momentum, and large populations of fast ions radially

outwards. As this can modify heating and current-drive profiles and potentially increase fast-ion losses,

the impact of sawteeth on confined fast ions is a subject of particular interest for future fusion devices. A

key challenge is to understand how the redistribution depends on fast-ion energy and pitch as well as on

plasma parameters and the sawtooth crash amplitude or period.

Collective Thomson Scattering (CTS) is well suited for studies of the mechanisms underlying fast-ion

redistribution by sawteeth, given its flexible measurement geometry which allows measurements in

specific regions of fast-ion phase space. Recently, at ASDEX Upgrade, the installation of a dedicated

CTS receiver for background monitoring has helped to significantly improve the acquisition and analysis

of CTS data, with CTS measurements of thermal and energetic ions in MHD-quiescent discharges

showing good agreement with results from other diagnostics and with neo-classical theory.

Building on this, we present the first CTS measurements of sawtooth-induced redistribution of fast ions

at ASDEX Upgrade and compare the results with those predicted with the Kadomtsev sawtooth model

implemented in TRANSP. We also discuss the results in light of those obtained using other fast-ion

diagnostics such as fast-ion D-alpha spectroscopy (FIDA), neutral particle analysers (NPA) and fast-ion

loss detectors (FILD) and consider what can be gained from a combined analysis of these measurements

using tomographic reconstruction.

This work has been carried out within the framework of the EUROfusion Consortium and has received funding

from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and

opinions expressed herein do not necessarily reflect those of the European Commission.

28

O-6: validating predictive models for fast ion profile relaxation

in burning plasmas

N. N. Gorelenkov1, W.W.Heidbrink

2, G. J. Kramer

1, J. Lestz

1, M. Podesta

1, M.A. Van Zeeland

3,

R. B. White1

1Princeton Plasma Physics Laboratory, Princeton University

2University of California, Irvin

3General Atomics, San Diego, California

The redistribution and potential loss of energetic particles due to MHD modes can limit the performance

of fusion plasmas by reducing the plasma heating rate. In this work, we present validation studies of a

1.5D or Critical Gradient Model (CGM) for Alfven eigenmode induced EP transport in NSTX and

DIII-D beam heated plasmas. In previous comparisons with a single DIII-D L-mode case, the CGM

model was found to be in surprisingly good agreement with measured AE induced neutron deficits [1].

Application to DIII-D advanced tokamak plasmas however, showed the need to expand the linear

stability analysis to nonperturbative regimes [2]. With the use of the fully kinetic nonperturbative code

HINST it is found that AEs show strong instability drive, γ/ω~ 20−30%, violating NOVA-K perturbative

assumptions. In the CGM, it is assumed that all fast ions are affected, even when they are not in

resonance with the underlying eigenmodes. This situation is natural for a plasma with strong collisions or

strong AE overlapping. As shown in Fig. 1 (left) both models agree with each other and both

underestimate the neutron deficit measured in the DIII-D shot.

On the other hand in NSTX the application of CGM shows agreement with the measured flux deficit

as shown in Fig. 1 (right). We discuss possible explanations of these DIII-D discrepancies between the

measurements and CGM predictions. We also attempt to understand these results with the help of the

guiding center code ORBIT. The ORBIT comparison allows insight into the underlying velocity space

dependence of the AE induced EP transport.

Figure 1. Neutron flux deficit computed with the help of CGM is compared with the measured deficit in DIIID shot

#153072 as shown in left figure. Shown on the right is the perturbative CGM application for NSTX plasma.

[1] W.W. Heidbrink, M. A. Van Zeeland, M. E. Austin, E. M. Bass, K. Ghantous, N. N. Gorelenkov, B. A.

Grierson, D. A. Spong, and B. J. Tobias, Nucl. Fusion 53, 093006 (2013).

[2] N. N. Gorelenkov, W.W. Heidbrink, J. B. Lestz, M. Podesta, M. A. V. Zeeland, and R. B.White, Proc. 25nd

IAEA Fusion Energy Conference, St. Petersburgh, Russia, CD-ROM file TH/P1-2, (2014).

29

O-7: measurement and simulation of deuterium balmer-alpha

emission from first - orbit fast ions and the application to

general fast - ion loss detection in the diii-d tokamak*

Nathan G. Bolte1, W.W. Heidbrink

1, D.C. Pace

2, M.A. Van Zeeland

2, Xi Chen

2

1University of California, Irvine, CA, USA 2General Atomics, San Diego, CA, USA


A new fast-ion diagnostic method is developed that utilizes passive emission of Balmer-alpha radiation

to determine fast-ion losses quantitatively. The purpose of this work is to put passive edge light

measurements on a quantitative footing by comparing the measurement and simulation of spectra from

beam prompt losses that charge exchange with the edge neutral population. Calibrated first-orbit spectra

are used to estimate the neutral density 2D profile by inverting the simulated spectra to find the best

neutral density—in a least squares sense—required to best match the experimental spectra. Successfully

measuring and simulating first-orbit spectra then effectively “calibrates” the system, allowing for the

quantification of more general fast-ion losses. Viewing geometry and the high energy of the fast ions

produce Doppler shifts that effectively separate the fast-ion contributions from the bright, cold edge light

while modulation of the fast-ion source allows for time-evolving background subtraction. The passive

fast-ion Dalpha simulation (P-FIDAsim) forward models the spectra of these first-orbit fast ions and

consists of a beam model, an ion orbit-calculating code, a collisional-radiative model, and a synthetic

spectrometer. Eighty-six experimental spectra are obtained (and simulated) using six different neutral

beam fast-ion sources and 13 different viewing chords for various operational conditions. Simulated

spectra have an overall Spearman rank correlation coefficient with the shape of experimental spectra of

58% with subsets of cases rising to a correlation of 80%. The inferred 2D neutral density shows the

expected increase toward each x-point with the average neutral density at 3.3×105 cm−3 at the magnetic

axis, 2.3×108 cm−3 in the core, 8.1×10

9 cm−3 at the plasma boundary, and 1.1×10

11 cm

−3 near the wall.

Sawtooth crashes are estimated to eject 1.2% of the fast-ion inventory globally, in good agreement with a

1.7% loss estimate made by the TRANSP code. As expected, sightlines that are sensitive to passing ions

observe larger sawtooth losses than sightlines that are sensitive to trapped ions.

* This work was supported by the US Department of Energy under DE-FC02-04ER-54698.

30

O-8: nonlinear energetic particle transport in the presence of

multiple alfvénic waves in iter

M. Schneller1, Ph. Lauber

1, S. Briguglio

2, X. Wang

1

1Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Deutschland

2ENEA C.R. Frascati, CP 65-00044 Frascati, Italy

E-mail Address of Submitting Author: [email protected]

As future fusion devices will exhibit large fractions of highly energetic particles (EP), the interplay of

fast ions with Alfvénic instabilities is an important topic in fusion research. Strong EP transport might

reduce the heating and current drive efficiencies, while losses could even damage the first wall. The aim

of the here presented work is to enhance the understanding of interaction mechanisms between EP and

multiple Alfvén waves in a realistic ITER case.

The focus lies on the 15 MA baseline scenario, where a “sea” of small-amplitude perturbations is

expected to be marginally unstable [1]. Based on quasi-linear estimates [2], the EP transport would be

rather low. The question of interest here is, whether the EP population will drive linearly stable or

weakly unstable modes nonlinearly unstable. As a consequence, dominolike transport can occur. Such

behavior has been found already in realistic ASDEX Upgrade double-mode simulations [3], which could

explain experimentally found EP losses [4]. Basis of the simulations is a nonlinear hybrid model, the

driftkinetic HAGIS code [5]. As crucial new elements of a realistic scenario, the perturbation structures,

frequencies and damping rates are taken as obtained from the gyrokinetic eigenvalue solver LIGKA [6].

Further, a new non-local damping mechanism has been implemented via accounting for a parallel

electric field Ell.

Although the nonlinear wave-particle interaction is calculated self-consistently within the HAGIS-

LIGKA model, at the present status, other nonlinearities such as the evolution of wave structure are not

included yet. Before extending the model in this direction, the expected effect of the radial wave

structure evolution is investigated: HAGIS-LIGKA results are compared to those of a different hybrid

code, HMGC [7], which already contains wave structure evolution. For that comparison, a newly

implemented phase space diagnostic, the so called Hamiltonian Mapping Technique [8] is used.

It allows for a detailed study of wave-particle interaction processes, especially in the view of

nonlinear saturation mechanisms.




References

[1] P. LAUBER. Plasma Physics and Controlled Fusion, 57 (5):054011 (2015).

[2] K. GHANTOUS ET AL. Phys. Plasmas, 19 (9):092511 (2012).

[3] M. SCHNELLER ET AL. Nucl. Fusion, 53 (12):123003 (2013).

[4] M. GARCÍA-MUÑOZ ET AL. Phys. Rev. Lett., 104:185002 (2010).

[5] S. PINCHES ET AL. Comput. Phys. Commun., 111 (13):133(1998).

[6] PH. LAUBER ET AL. J. Comp. Phys., 226 (1):447 (2007).

[7] S. BRIGUGLIO ET AL. Phys. Plasmas, 5 (9):3287 (1998).

[8] S. BRIGUGLIO ET AL. Phys. Plasmas, 21 (11):112301(2014).

31

O-9: experimental observations of fast-ion losses on kstar

J.-H. Kim1,2

, J.-Y. Kim2, T.N. Rhee

1, M. Isobe

3, K. Ogawa

3, K. Shinohara

4, M. Garcia-Munoz

5,

Y.M. Jeon1, S.H. Kim

6, and S. W. Yoon

1

1National Fusion Research Institute, 169-148 Gwahak-ro, Yuseong-gu, Daejeon 305-806, Korea

2Korea University of Science and Technology, Gajeong-ro, Yuseong-gu, Daejeon 305-350, Korea

3National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan

4Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan

5University of Seville, Av de la Reina Mercedes, 41012 Seville, Spain

6Korea Atomic Energy Research Institute, 111 Daedeok-Daero, Yuseong-gu, Daejeon 305-353, Korea

E-mail address of submitting author: [email protected]

Confinement and transport of fast-ions in the fusion plasmas becomes crucial as the performance of the

fusion device has been elevated along with increase of heating power. As known well, loss of the fast-

ions (auxiliary heated ions, fusion products and so on) can degrade the fusion performance and damage

the first-wall. On KSTAR, mechanism of beam-ion loss has been studied experimentally through the

energetic particle diagnostics such as scintillator-based fast-ion loss detectors (FILD), compact neutral

particle analyzer (NPA) and so on. Various factors, affecting fast-ion loss, such as ELMs, edge magnetic

perturbations, tearing modes, energetic particle modes have been investigated. Most clear response on

the fast-ion loss is the ELM-induced one, and it has been found that the edge magnetic perturbations

having various field spectra could cause different non-axisymmetric loss patterns. To understand the fast-

ion loss behaviour responding to the non-axisymmetric magnetic perturbations, full 3-D orbit simulations

using LORBIT and F3D-OFMC have been devoted and the calculated change in the pitch-angle

distribution based on the vacuum field is matched well with the FILD measurements in several cases.

Not only vacuum field simulation but also plasma-response will be considered to explain the discrepancy

between the simulations and the experimental results depending on plasma β. In addition to the fast-ion

loss associated with the edge activities, interactions with core MHD activities such as tearing modes and

energetic particle modes have been observed. On the contrary to the edge-activity cases, fast-ion loss

correlated with core activities seems to be case-sensitive since the interplay of the fast-ion orbit exploring

the core region with the rotating modes may have to be synchronized, leading to the resonant interaction

and loss. Finally near-term KSTAR energetic particle research plan is discussed.


32

O-10: the impact of anisotropy and flow on magnetic

configuration, and stability

M.J. Hole, M. Fitzgerald, Z. Qu, B. Layden

Plasma Theory and Modelling Group , Australian National University, ACT 0200, Australia


Recently, equilibrium models and reconstruction codes have been generalised to include physics of

anisotropy and toroidal flow[1]. These codes have been used to explore the impact on the magnetic

configuration in regimes with large neutral beam heating, as well as determine the impact on particular

discharges [2]. In parallel to these developments, a single adiabatic extensions of MHD stability models

that capture anisotropy and flow has been developed [3], and together with CGL models, implemented

into the ideal MHD stability code MISHKA-ATF[4]. In this work we highlight the differences in the

CGL / single adiabatic model continuum, and report on the impact of anisotropy and flow on the

equilibrium, frequency and mode structure of a range of energetic particle driven modes in MAST. We

also update development of generalisation of the wave-particle interaction code HAGIS to simulate

plasmas with anisotropy and flow.

Figure 1: n=1, =0 continuous mode spectrum for MAST 29221@190ms EFIT-TENSOR reconstructions, for

isotropic and anisotropic cases. The lower plots show calculations of the mode structure using MISHKA-ATF,

showing a broader mode structure in the anisotropic case.

[1] M. Fitzgerald, L. C. Appel, M. J. Hole, Nucl. Fusion 53 (2013) 113040

[2] Z S Qu, M Fitzgerald and M J Hole, Plasma Phys. Control. Fusion 56 (2014) 075007

[3] M Fitzgerald, M J Hole and Z S Qu, Plasma Phys. Control. Fusion 57 (2015) 025018

[4] Z.S. Qu, M.J. Hole and M. Fitzgerald, Plasma Phys. Control. Fusion, submitted

88kHz 75kHz

anisotropicisotropicn=1, =0 n=1, =0

f /fA f /fA

ss

0 1

0

1

0 1

0

1

s s

p||/p = 1.7 at s=0.5 outboard


33

O-11: sensitivity of alpha-particle–driven alfvén eigenmodes to

q-profile variation in iter scenarios

P. Rodrigues1, A. C. A. Figueiredo

1, L. Fazendeiro

1 J. Ferreira

1, R. Coelho

1, F. Nabais

1,

D. Borba1, N. F. Loureiro

1, A. Polevoi

2, S. D. Pinches

2, and S. E. Sharapov

3

1Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa,

Portugal. 2ITER Organization, Route de Vinon-sur-Verdon, 13067 St Paul-lez-Durance Cedex, France.

3CCFE, Culham Science Centre, Abingdon OX14 3DB, United Kingdom


Plasma heating during the burning regime in tokamak reactors will rely upon the energy of fusion-born

alpha-particles which must be kept confined to keep the plasma hot and prevent wall damage. However,

such particles can drive Alfvén Eigenmodes (AEs) unstable and be thus transported away from the

plasma core, which would hamper the burning process. The complex interplay between energetic supra-

thermal particles and AEs is still not fully understood and recent research concerning ITER [1, 2, 3] has

been focusing on the 15 MA baseline scenario [4].

In this work, the ASPACK [3] suite of codes is used to find how the linear-stability properties of AEs

change in response to small variations of the background profiles. Of particular interest are the net

growth-rate, wave numbers, and frequency of the most linearly-unstable AEs. These properties are

shown to be significantly affected by small changes of the safety-factor profile. The consequences of

these results for stability predictions of alpha-particle–driven AEs in burning plasmas are also discussed.

References

[1] S. D. Pinches et al., Phys. Plasmas 22, 021807 (2015).

[2] Ph. Lauber, Plasma Phys. Control. Fusion 57, 054011 (2015).

[3] P. Rodrigues et al. “Systematic linear-stability assessment of Alfvén eigenmodes in the

presence of fusion a-particles for ITER-like equilibria”, accepted in Nucl. Fusion (2015).

[4] A. R. Polevoi et al., J. Plasma Fusion Res. SERIES 5, 82 (2002).

34

O-12: observation of chirping modes in jet at frequencies above the

alfvén frequency

F. Nabais1, D. Borba

1, R. Coelho

1, L. Fazendeiro

1 J. Ferreira

1, A. Figueiredo

1, L. Fitzgerald

2, L. Menezes

1,

P. Rodrigues1, S. Sharapov

2 and JET Contributors

§

EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, UK 1Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal.

2CCFE, Culham Science Centre, Abingdon OX14 3DB, UK.


Modes propagating in the range of frequencies comprised between the Alfvén frequency and the cyclotron

frequency are not normally observed in currently operating tokamaks. Notable exceptions are spherical tokamaks,

like NSTX and MAST, and the conventional tokamak DIII-D operating with low magnetic field, where modes in

this range of frequencies have been observed when super-Alfvénic beams are injected into the plasma [1, 2, 3].

Moreover, these modes might be destabilized in ITER [3] and they may be important for stochastic heating of

thermal ions [4] as well as for diagnostic purposes.

This paper reports on the observation of fast chirping modes with frequencies above the Alfvén frequency in JET

experiments. Contrary to the cases mentioned above, the modes observed in JET were destabilized by ICRH

instead of NBI energetic ions. These experiments used low-density deuterium plasmas and high ICRH power,

allowing a large population of energetic ions in the MeV range to build up in the plasma [5]. The observed modes

share many characteristics with those described in [1, 2, 3]. They exhibit a fast chirping behavior and propagate

both in the counter and co-current direction, appearing normally in groups with different bands forming

sometimes intricate patterns. The frequency correlates with the magnetic field, suggesting an Alfvénic nature. The

behavior of these modes is correlated with other instabilities, in particular with tornado modes and monster

sawtooth crashes, and they seem to have little or no influence on the loss of fast ions from the plasma.

[1] E.D. Fredrickson et al. Phys. Rev. Lett. 87, 145001 (2001)

[2] L.C. Appel et al. Plasma Phys. Control. Fusion 50, 115011 (2008)

[3] W.W. Heidbrink et al. Nucl. Fusion 46, 324 (2006)

[4] N.N. Gorelenkov et al. Nucl. Fusion 43, 228 (2003)

[5] F. Nabais et al. Nucl. Fusion 50, 115006 (2010)

Acknowledgments -IST activities received financial support from “Fundação para a Ciência e Tecnologia” through project

UID/FIS/50010/2013.

§See the Appendix of F. Romanelli et al., Proceedings of the 25th IAEA Fusion Energy Conference 2014, Saint Petersburg,

Russia

35

O-13: experimental investigation of the radial structure of

energetic particle driven modes

L. Horváth1*

, G. Papp2,3

, G. I. Pokol1, Ph. Lauber

3, G. Por

1, A. Gude

3, V. Igochine

3 and the ASDEX

Upgrade Team3

1Institute of Nuclear Techniques, BME, Budapest, Hungary

2Max-Planck/Princeton Center for Plasma Physics

3Max Planck Institute for Plasma Physics, Garching, Germany


The understanding of energetic particle driven modes in tokamaks plays a key role regarding future

burning plasma experiments. Energetic particles (EPs) can excite various instabilities. Alfvén

eigenmodes (AEs) are often excited by EPs and in addition to these MHD normal modes, there are also

energetic particle modes (EPMs) characterized by strong dependence on the fast-ion distribution

function. One of the main open questions concerning EP driven instabilities is the non-linear evolution of

the mode structure, because these instabilities constitute such a system where kinetic and MHD

non-linearities can both be important making it difficult to describe the phenomenon [1].

The aim of the present contribution is to investigate the properties of beta-induced AEs (BAEs) and EP

driven geodesic acoustic modes (EGAMs) observed in the ramp-up phase of off-axis NBI heated

ASDEX Upgrade (AUG) discharges [2]. The interest is mostly focused on the changes in the mode

structure of BAEs/EGAMs during the non-linear “chirping” phase. The analysis was carried out

primarily using soft X-ray diagnostics (SXR), because these modes were well visible on several SXR

line-of-sights which made it possible to analyse their spatial structure. The rapidly changing mode

frequency and the low signal-to-noise ratio are handled with an advanced continuous linear time-

frequency transform based method [3].

Our investigation shows that in case of the observed down-chirping BAEs the changes in the radial

eigenfunction are smaller than the uncertainty of our measurement. In case of rapidly upward chirping

EGAMs the analysis consistently shows shrinkage of the mode structure. This could be explained by that

the resonance in the velocity phase space moves towards more passing particles which have narrower

orbit width.

References

[1] W. W. Heidbrink, Physics of Plasmas 15, 055501 (2008)

[2] Ph. Lauber et al., Presented at the 13th IAEA TCM, Beijing, China (2013)

[3] L. Horváth et al., 41st EPS Conference on Plasma Physics 38F, P2.008 (2014)

“This work has been carried out within the framework of the EUROfusion Consortium and has received funding


opinions expressed herein do not necessarily reflect those of the European Commission.”


http://dx.doi.org/10.1063/1.2838239

http://www.phy.pku.edu.cn/fsc/admin/fileadmin/upfile/Lauber.Ph.-D.pdf

http://ocs.ciemat.es/EPS2014PAP/pdf/P2.008.pdf

36

O-14: verification and validation of gyrokinetic particle

simulation of fast electron driven beta-induced alfvén

eigenmode on hl-2a tokamak*

Wenlu Zhang1,2

, Junyi Cheng1, Wei Chen

3, Limin Yu

3, Xuantong Ding

3

1Institute of Physics, Chinese Academic of Science, Beijing 100190, China

2University of Science and Technology of China, Hefei, Anhui 230026, China

3Southwestern Institute of Physics, Chengdu, Sichuan 610041, China


A verification and validation study is carried out for a sequence of fast-electron driven beta-induced

Alfven eigenmode (e-BAE) in HL-2A tokamak plasma. The fast electron driven beta Alfvén eigenmode

(e-BAE) in toroidal plasmas is investigated for the first time using global gyrokinetic particle

simulations, where the fast electrons are described by the drift kinetic model. The phase space structure

shows that only the processional resonance is responsible for the e-BAE excitations while fast-ion driven

BAE can be excited through all the channels such as transit, drift-bounce, and processional resonance.

Radial symmetry breaking around the rational surface is observed as expected due to the non-

perturbative effects in the kinetic simulations, and the poloidal mode structure shows a different rotation

direction for e-BAE and i-BAE simulations, this is due to the different direction of toroidal procession in

the e-BAE and i-BAE excitations.

* Supported by National Special Research Program of China For ITER

37

O-15: excitation of waves by a spiraling ion beam in a large

magnetized plasma

S. Tripathi1, B. V. Compernolle

1, W. Gekelman

1, P. Pribyl

1, W. Heidbrink

2

1Physics and Astronomy, University of California at Los Angeles, Los Angeles, CA 90095,USA

2Physics and Astronomy, University of California at Irvine, Irvine, CA 92697, USA


An ion source (25 keV, 10 A, 0.3 Hz rep rate, 0.5–1.5 ms pulse-width) has been constructed for

performing fusion-relevant fast-ion studies on the Large Plasma Device (LAPD), which produces a

cylindrical magnetoplasma (19 m long, 0.6 m diameter) with 10–20 ms pulse width and 1-Hz repetition

rate. The ion source [1] was used to inject a spiraling hydrogen ion beam into the ambient plasma with

single and two ion species (n ≈ 1010

– 1012

cm-3

, Te = 5.0– 12.0 eV, B = 0.06–0.18 T, He+ and H

+ ions).

The interaction of the beam with the plasma was diagnosed using retarding-field energy analyzers, three-

axis magnetic-loops, and Langmuir probes. Measurements of the beam profiles at multiple axial

locations evinced a spiraling ion-beam (J ≈ 50–140 mA/cm2, pitch-angle ≈ 53°) that traveled at Alfvénic

speed (beam-speed/Alfvén-speed = 0.2–1.2). A multitude of waves were spontaneously excited by the

beam in the drift, shear Alfvén, ion cyclotron, and lower hybrid frequency ranges. This presentation

gives an overview of the experiment and provides details of the resonant excitation of shear Alfvén

waves through Doppler-shifted ion-cyclotron resonances (DICR) with the ion beam [2]. Parameters of

the beam and ambient plasma were varied to examine the resonance conditions under a variety of

scenarios. The experimental results demonstrate that the DICR process is particularly effective in

exciting left-handed polarized shear Alfvén waves that propagate in the direction opposite to the ion

beam.

References:

[1] Tripathi et. al., Rev. Sci. Instrum. 82, 093501 (2011)

[2] Tripathi et. al., Phys. Rev. E 91, 013109 (2015)

Work jointly supported by U. S. Department of Energy (Grant No. DOE-DE-FC02-07ER-54918) and National

Science Foundation, USA (Grant No. NSF-PHY-1036140) and performed at the Basic Plasma Science Facility,

UCLA.


38

O-16: analysis of energetic particle driven Alfvén instabilities in

3D toroidal systems using a global gyrokinetic model

D. A. Spong1, I. Holod

2

1Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831--‐6169, U. S. A.

2University of California - Irvine, Department of Physics and Astronomy, Irvine, CA 92697 U. S. A.

Recently there has been increasing interest in the physics of toroidal devices with 3D field modifications.

Energetic particle physics can play an important role in these devices for many of the same reasons as in

axisymmetric tokamaks (protection of PFCs, loss of heating efficiency and diagnostic uses). 3D

configurations modify EP physics through: emergence of new gap structures, larger finite orbit width

effects, and the need to consider mode families with multiple toroidal mode numbers. To address these

issues, the GTC global gyrokinetic PIC model has been adapted to 3D VMEC equilibria and provides a

new method for the unified analysis of Alfvénic instabilities in stellarators, 3D tokamaks, and helical

RFP states. The gyrokinetic orderings (k||/k⊥ << 1, ω/Ωci << 1, ρEP/L << 1) are applicable to a wide

range of energetic particle driven instabilities that have been observed in 3D configurations. This talk

will describe the GTC global gyrokinetic model, its adaptation to 3D systems, and recent results.

Applications of this model to stellarators have indicated that a variety of different Alfvén instabilities can

be excited, depending on the toroidal mode number, fast ion average energy and fast ion density profile.

TAE, EAE and GAE modes have been found in the simulations, depending on the mode family and fast

ion profiles used. The dynamical evolution of the instabilities shows the field period coupling between

n and n + Nfp, as expected for 3D configurations. Applications to other devices and the development of

gyrofluid models that can capture relevant physics aspects of the gyrokinetic models will also be

discussed.

Figure 1 – 3D and 2D (fixed toroidal plane)mode structure of an n – 3 TAE instability in the LHD stellarator.

Acknowledgment: Work supported by U.S. Department of Energy, Office of Science Contract No. DE--‐AC05--‐00OR227250020and under the U.S. DOE SciDAC GSEP Center.

39

O-17: impact of localized ecrh on nbi and icrh driven alfvén

eigenmodes in the asdex upgrade tokamak

M. Garcia-Munoz1,2

, M. A. Van Zeeland3, S. Sharapov

4, I. G. J. Classen

5, B. Bobkov

2,

J. Galdon-Quiroga1, B. Geiger

2, V. Igochine

2, P. Lauber

2, N. Lazanyi

6, F. Nabais

7,

D. C. Pace3, M. Rodriguez-Ramos

1, L. Sanchis-Sanchez

1, M. Schneller

2, A. Snicker

8,

J. Stober2 and the ASDEX Upgrade Team

1FAMN Department, Faculty of Physics, University of Seville, Seville, Spain

2 Max Planck Institut fur Plasmaphysik, Garching, Germany


4Culham Center for Fusion Energy, Culham Science Center, Abingdon, Oxfordshire, UK

5FOM-Institute DIFFER, Nieuwegein, The Netherlands

6BME NTI, Budapest, Hungary

7Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Portugal

8Aalto University, Espoo, Finland

NBI driven Alfvén Eigenmodes (AEs) are routinely obtained in the ASDEX Upgrade (AUG) toakamak

during the current ramp-up phase with early NBI heating and reversed q-profile. Most commonly

observed AEs comprise Reversed Shear Alfven Eigenmodes (RSAEs) and Toroidal Alfven Eigenmodes

(TAEs). Recent experiments have been carried out in AUG to affect the observed AE activity via

localized ECRH. ECRH is applied a few ms after the onset of the AE activity at different radial positions

to study the impact that localized ECRH has on the observed AE activity. For ECRH injection near qmin,

(RSAEs location) the overall mode activity is significantly reduced. While in DIII-D, the unstable modes

shift from strong RSAEs to weaker global TAEs and reminiscent RSAEs are visible only at their highest

frequencies during their transition to TAEs [1], in AUG, almost all mode activity disappears with ECRH

injection near qmin. With reduced or no mode activity, the fast-ion confinement is significantly improved,

in fact, the fast-ion profile measured with Fast-Ion D-Alpha (FIDA) spectroscopy matches classical

TRANSP predictions. In agreement with this observation, and with classical fast-ion profiles, no fast-ion

losses induced by AEs are observed by the Fast-Ion Loss Detectors (FILD) systems. Similar experiments

with ICRH driven AEs do not exhibit the same reduction in RSAE activity with ECRH near qmin. Future

sensitivity experiments and modelling will focus on understanding this difference and the overall impact

that the slightly ECRH modified q-profile, Te and fast-ion pressure may have on the observed AE

activity. Stability and transport analysis have been started using MISHKA/CASTOR-K, LIGKA/HAGIS

and ASCOT codes and will be discussed.

[1] M.A. Van Zeeland, et. al., Plasma Phys. Control. Fusion 50 035009 (2008)

40

O-18: the study of nbi-driven chirping mode properties and radial

location by heavy ion beam probe in the tj-ii stellarator

A.V. Melnikov1, 2

, E. Ascasibar3, A. Cappa

3, L.G. Eliseev

1, C. Hidalgo

3, A.S. Kozachek

4, L.I. Krupnik

4,

M. Liniers3, S.E.Lysenko

1, J.L. dePablos

3, S.V. Perfilov

1, V.N. Zenin

1,

HIBP group1, 3, 4

and TJ-II team2

1 National Research Centre “Kurchatov Institute”, 123182, Moscow, Russia

2 National Research Nuclear University “MEPhI”, Moscow, Russia

3 Fusion National Laboratory, CIEMAT, 28040, Madrid, Spain

4 Institute of Plasma Physics, NSC KIPT, 310108, Kharkov, Ukraine

Alfven Eigenmodes were studied in low magnetic shear flexible heliac TJ-II (B0=0.95 T, <R>=1.5 m,

<a>=0.22 m) NBI heated plasmas (PNBI1.1 MW, ENBI=32 keV) by Heavy Ion Beam Probe (HIBP)

[1, 2, 3]. The L-mode hydrogen plasma was investigated at various magnetic configurations with

rotational transform a/2q ~ 1.5 - 1.6. Co-, counter and balanced beam injection were explored.

HIBP is capable to measure simultaneously the oscillations of the plasma electric potential, density and

poloidal magnetic field. Earlier studies have shown the chirping modes with 250 kHz< fAE <380 kHz at

the combined ECR and NBI heated plasmas with low density ne = (0.3 – 1.5)×1019

m-3

[3, 4]. Here we

report the observation of the chirping modes with the similar properties with NBI heating only (no

ECRH) at the similar densities, obtained due to Lithium treatment of the vacuum vessel [5]. Thus one

may suggest that the ECRH is not necessary ingredient to obtain chirping modes in TJ-II by itself, rather

an instrument, helping to get low density discharges. HIBP shows the location of the specific AE

chirping mode at 0.4 < < 0.8. Dual HIBP [6], consisting of the two HIBPs, separated at ¼ of the torus

shows the high coherence between the plasma potential and density oscillations during the period of the

frequency burst.

[1] R. Jiménez-Gómez et al Nuclear Fusion 51 (2011) 033001

[2] A.V. Melnikov et al Nuclear Fusion 50 (2010) 084023

[3] K. Nagaoka et al Nuclear Fusion 53 (2013) 072004

[4] A. Cappa et al 25-th IAEA FEC 2014, EX/P4-46. Nucl. Fusion, submitted.

[5] F.L. Tabares et al Plasma Phys. Control. Fusion 50 (2008) 124051.

[6] J.L. De Pablos et al SOFT 2014, P1.060. Fusion Engineering and Design, Submitted.

41

O-19: simulation study of profile stiffness of fast-ions

interacting with multiple alfvén eigenmodes

Y. Todo1, 2

, M. A. Van Zeeland3, W. W. Heidbrink

4

1National Institute for Fusion Science, Toki, Gifu 509-5292, Japan

2SOKENDAI (The Graduate University for Advanced Studies), Toki, Gifu 509-5292, Japan

3General Atomics, PO Box 85608, San Diego, CA 92186, USA

4University of California, Irvine, CA 92697, USA


A multi-phase simulation, which is a combination of classical simulation and hybrid simulation for

energetic particles interacting with a magnetohydrodynamic (MHD) fluid including neutral beam

injection (NBI), slowing-down, and pitch angle scattering, was applied to DIII-D discharge #142111

[1,2]. The large fast ion pressure profile flattening and the electron temperature fluctuations brought

about by multiple Alfvén eigenmodes (AEs) were successfully reproduced with the simulation. Recently,

we performed an NBI power scan using the equilibrium data of DIII-D discharge #142111 to investigate

fast ion profile stiffness. The range of the power scan is from 1.56MW to 12.5MW with the experimental

power 6.25MW. The simulation results of stored fast ion energy versus NBI power are shown in Fig. 1.

We see in the figure the stored fast ion energy increases with the NBI power but reduced from the

classical level. For the lowest power 1.56MW, multiple AEs are already destabilized, but the stored

energy is close to the classical level because only the AEs located close to the plasma center are

destabilized and the amplitudes are low. Saturation of stored fast ion energy expected for profile stiffness

does not take place for the cases investigated. Detailed analyses of resonance overlap will be performed

and the condition for the profile stiffness will be discussed.

Figure 1. Stored fast ion energy versus NBI power for classical and multi-phase hybrid simulation

[1] Y. Todo et al., Nucl. Fusion 54 (2014) 104012.

[2] Y. Todo et al., to appear in Nucl. Fusion 55 (2015).

42

O-20: impact of localized electron cyclotron heating on alfvén

eigenmodes in diii-d*

M.A. Van Zeeland1, A. Cappa

2, W. W. Heidbrink

3, S.E. Sharapov

4, E.M. Bass

5, C. Collins

3,

M. Garcia-Munoz6, G.J. Kramer

7, Z. Lin

3, D.C. Pace

1, C. Petty

1, D. Spong

8


Email Address of Submitting Author: [email protected] 2 Laboratorio Nacional de Fusión -CIEMAT. 28040 Madrid, Spain

3University of California at Irvine, Irvine, CA 92697, USA

4CCFE, Culham Science Centre, Abingdon, Oxon, OX14 3DB, UK

5University of California San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0417, USA

6Max-Planck-Institut für Plasmaphysik, Euratom Association, Garching, Germany.

7Princeton Plasma Physics Laboratory, PO Box 451, Princeton, NJ 08543-0451, USA

8Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA

Localized electron cyclotron heating (ECH) can have a dramatic effect on neutral beam driven Alfvén

eigenmode activity in DIII-D reversed magnetic shear plasmas. The most commonly observed effect is a

shift in the dominant observed modes from a mix of reversed shear Alfvén eigenmodes (RSAEs) and

toroidicity induced Alfvén eigenmodes (TAEs) to a spectrum of weaker TAEs when ECH is deposited

near the shear reversal point (qmin) [1,2]. ECH deposition near the magnetic axis typically increases the

unstable mode amplitudes and resultant fast ion transport. A recent experiment to understand the physical

mechanisms responsible for this shift in AE stability utilized a simplified oval geometry and, in addition

to ECH injection location, included variations of current ramp rate, ECH injection timing, beam injection

geometry (on/off-axis), and neutral beam power. Essentially all variations carried out in this experiment

were observed to change the impact of ECH on AE activity significantly. In some cases, RSAEs were

observed to be more unstable with ECH near qmin as opposed to near q0, in contrast to the original DIII-D

experiments. It is found that for many of the intervals with minimal RSAE activity, or RSAEs with a

much reduced frequency sweep range, that the geodesic acoustic mode (GAM) frequency at qmin is very

near or above the nominal TAE frequency - suggesting the so-called beta suppression mechanism [3] is

important in these plasmas. A simple analytic model that incorporates this reduction in RSAE chirp

range is in agreement with the observed spectra and appears to capture the relative balance of TAE or

RSAE like modes. A database analysis of these discharges also shows a persistent trend for lower mode

amplitude and a shift from TAE to RSAE dominated as the current penetrates and qmin decreases.

Detailed non-perturbative calculations of the observed shift in RSAE stability with ECH deposition are

underway and will also be presented.

*This work was supported by the US Department of Energy under DE-FC02-04ER-54698, DE-FG03-

94ER54271, DE-FG02-08ER54984, DE-AC02-09CH11466, DE-SC0012551,DE-AC05-00OR22725.

[1] M.A. Van Zeeland, et.al PPCF 50 (2008) 035009

[2] M.A. Van Zeeland, et.al Nucl. Fusion 49 (2009) 065003

[3] Fredrickson et al Phys. Plasmas 14 (2007) 102510

43

O-21: coupled kinetic-fluid simulation of runaway electron

dynamics

G. Papp1, A. Stahl

2, Ph. W. Lauber

1 and T. Fülop

2

1Max Planck Institute for Plasma Physics, Garching, Germany.

2Department of Applied Physics, Chalmers University, Göteborg, Sweden

Reliable runaway electron (RE) mitigation after disruptions is one of the most important challenges for

safe ITER operation [1]. A proper understanding of the generation and losses of REs is therefore

essential. A full MHD simulation of the disruption is a complex and computationally demanding task.

Therefore, reduced dimension “fluid-type" models are employed to describe the evolution of plasma

parameters during disruptions with reasonable accuracy. One of these codes is GO [2], which uses a

self-consistent, onedimensional model to calculate the evolution of electric field, plasma parameters and

runaway current and is also capable of taking into account impurity injection using a collisional-radiative

model based on ADAS data. GO has already been applied to various tokamaks to better understand the

runaway evolution during mitigated or unmitigated disruptions [1, 2], and its physics model is being

continuously extended.

There are several applications however, that demand the knowledge of the electron distribution function.

Accurate estimates of wall damage, calculation of the interaction with partially ionised high-Z materials,

calculation of synchrotron or bremsstrahlung emission (for diagnostic purposes), possibilities for

particle-wave interactions, even constraining equilibrium reconstructions requires an energy- and pitch

resolved distribution. We use the 2 dimensional Fokker-Planck solver CODE [3] to calculate the

momentum-space distribution of runaway electrons for time-evolving plasma parameters. As the next

step in self-consistent runaway modelling, we are coupling GO with CODE to obtain the 3 dimensional

evolution of the fe(pll; p┴, r, t) electron distribution. In the future, coupling with more sophisticated

solvers (e.g. the 3 dimensional LUKE [4]) is planned.

In this paper we report on the recent progress and the complexities involved with implementing such

self-consistent calculations. We also present the implications of the coupled model and its components in

the view of recent experimental results [5].

References

[1] E. M. Hollmann et al., PoP 22 021802 (2015)

[2] G. Papp et al., Nuclear Fusion 53 123017 (2014)

[3] A. Stahl et al., PRL 114 115002 (2015)

[4] J. Decker et al., PSFC/RR-05-3 (2005)

[5] G. Pautasso et al., EPS Conference (2015)

This research was partially funded by the Max-Planck/Princeton Center for Plasma Physics. This work has been

carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom

research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed

herein do not necessarily reflect those of the European Commission.

44

O-22: study of disruption generated runaway electrons on

j-text tokamak

Z. Y. Chen, D. W. Huang, Y. H. Luo, Y. Tang and J-TEXT Team

College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan,

430074, China


Runaway currents following disruptions have an important effect on the first wall for the next

generation tokamak. The behaviors of runaway currents in massive gas injection (MGI) induced

disruptions have been investigated in the J-TEXT tokamak. It is found that MGI of He or Ne

result in runaway free shutdown with different amount of gas injection. Moderate amount

injection of Ar prone to produce significant runaway current. A fast frame camera diagnostics has

been developed to study the penetration of impurities gas jet on J-TEXT. The cold front induced

by the gas jet propagated into the plasma interior in the order of 200 m/s. The cold front was

stopped at the location near the q=2 surface. The resonant magnetic perturbation (RMP) has been

applied to reduce runaway production during disruptions. It is found that both the amplitude and

the length of runaway current can be reduced by the application of RMP during the disruptions as

shown in Fig.1.

Fig.1. Runaway current induced by Ar MGI at 0.4s. With the application of RMP, both the amplitude and the

length of runaway current are reduced.


45

list of posters:

Poster Session I – Wednesday 2nd September, 15.05 -17.15

P-1 M. Gryaznevich Towards Compact Fusion Reactor: Fast Particle Issues

P-2 Y. Kolesnichenko Effects of large-scale perturbations on the transport of

energetic ions in tokamaks

P-3 K. Schoepf TAE induced alpha particle and energy transport in ITER

P-4 D. Darrow Beam ion susceptibility to loss in NSTX-U plasmas

P-5 V. Yavorskij Experimental investigation of ELM-induced fast-ion

losses at the ASDEX upgrade tokamak

P-6 R. Farengo The effect of perturbed electric fields and atomic

processes on the redistribution of energetic particles

P-7 S. Yamamoto Studies of fast ion losses caused by MHD instabilities by

using Faraday cup type lost ion probe in Heliotron J

plasmas

P-8 M. Homma Simulation Study of Triton Confinement and Nuclear

Reaction in the Deuterium Plasma Experiment at LHD

P-9 H. Yamaguchi Evaluation of fluxes of lost alphas for gamma-ray

diagnostics in ITER

P-10 S. Murakami Development of nonlinear collision operator for the

Monte Carlo simulation code in toroidal plasmas

P-11 F. Jaulmes Numerical and experimental study of the redistribution of

energetic and impurity ions by sawteeth in ASDEX

Upgrade experiments

46

P-12 T. Kurki-Suonio Effect of the European design of TBMs on ITER wall

loads due to fast ions in the baseline (15MA),

hybrid (12.5MA), steady-state (9MA) and

half-field (7.5MA) scenarios

P-13 D. Liu Comparison of fast ion confinement during on-axis and

off-axis neutral beam experiments on NSTX-U

P-14 M. Nocente Numerical investigation of fast ion losses induced by

resonant magnetic perturbation and edge localized

modes at ASDEX Upgrade

P-15 B. Layden Pressure anisotropy and flow suppress diamagnetic holes

in high-beta tokamaks

P-16 K. Shinohara Investigation of fast ion behavior using orbit following

Monte-Carlo code in magnetic perturbed field in KSTAR

P-17 N. Bolte Fast Particle Physics and its Connection to Performance

on C-2

P-18 L. Xu Fishbone activity in EAST neutron beam injection plasma

P-19 Z. Lin Progress in gyrokinetic particle simulation of Alfven

instabilities

P-20 N. Lazanyi Experimental investigation of ELM-induced fast-ion

losses at the ASDEX Upgrade tokamak

P-21 M. Mantsinen Analysis of ICRF heating and ICRF-driven fast ions in

recent JET experiments

P-22 J. Ferreira A stability study of α-particle driven Alfvén eigenmodes

in JET D-T plasmas

47

I-1 P. Schneider Overview of diagnostic enhancements and physics studies

of confined fast-ions in ASDEX Upgrade

I-2 I. Furno Non-diffusive transport of suprathermal ions in toroidally

magnetized plasmas

I-3 W. Heidbrink Experimental determination of the threshold for “stiff”

fast-ion transport by Alfven eigenmodes

I-4 D. Pfefferle Alpha particle confinement in the European DEMO

I-5 M. Schneider Modelling 3rd harmonic Ion Cyclotron acceleration of D

beam for JET Fusion Product Studies experiments

48

P-1: towards compact fusion reactor: fast particle issues

M Gryaznevich

Tokamak Energy Ltd, Culham Science Centre, Abingdon, OX14 3DB, UK

Email of Submitting Author: [email protected]

Fusion reactor based on a compact high field Spherical Tokamak (ST) and specific issues connected with

the fast particle and alpha particle physics are discussed in this talk.

Encouraging results on a strong favourable dependence of electron transport on higher toroidal field (TF)

in Spherical Tokamaks [1] open new prospects for a high field ST as a very compact fusion reactor. The

combination of the high (ratio of the plasma pressure to magnetic pressure), which has been achieved

in STs [2], and the high TF that can be produced by HTS TF magnets [3], opens a path to lower-volume

burning plasma devices and fusion reactors.

As a step towards such compact fusion reactor, a new tokamak, ST40, is being constructed at Culham,

UK. The main goal of this compact device (R0 ~ 0.4-0.5m, R/a ~ 1.6-1.8, Bt/Ipl = 3T/2MA, k~2.5, pulse

duration ~ several seconds) is to achieve predicted high performance of an ST at high field, aiming at the

burning plasma conditions. Update on the construction status of ST40 will be given.

Neutral beam injection with two different energies, Eb ~ 40keV and ~120keV, will be used in ST40 for

heating and current drive (CD). New approach to optimization of the current drive in a compact ST

reactor is based on a possibility to produce significant toroidal rotation in an ST using optimized neutral

beam injection (e.g. with reduced Eb). However, CD and neutron production (where beam-plasma

interaction will play a dominant role in D-D operations), require higher Eb. These result in several

challenges in the fast particle physics area due to large orbits and small cross-section of the ST40.

Results of optimization of the NBI for direct CD and for the torque, using NUBEAM, NFREYA, FIFPC

and ASCOT codes, will be presented to show that these conditions are quite different in the optimized

beam energy and in the launch geometry due to difference in the beam deposition and in the fast ion

losses. Due to relatively low for an ST toroidal beta (at high toroidal field), TAE modes may play

significant role.

Full-orbit simulations of alpha particles in a compact ST reactor show a possibility of a significant

reduction of the necessary (for α containment) plasma current. This reduction is very important as it

could reduce the auxiliary power required for CD in a solenoid-less ST reactor, which may significantly

enhance the economics of the energy production. Although ST40 is not designed for tritium operations,

trace of T experiments are under consideration.

[1] VALOVIC, M., et al, (2009) Nucl Fus 49 075016.

[2] GRYAZNEVICH, M., et al, “Achievement of Record beta in START Spherical Tokamak“(1998) Phys Rev Lett

50 3972.

[3] GRYAZNEVICH, M., et al, “Progress in applications of HTS in Tokamak Magnets” (2013) Fus Eng & Des 88

1593–1596.

49

P-2: effects of large-scale perturbations on the transport of

energetic ions in tokamaks

Ya.I. Kolesnichenko, O.S. Burdo, V.V. Lutsenko, B.S. Lepiavko, M.H. Tyshchenko, Yu.V. Yakovenko

Institute for Nuclear Research, Prospekt Nauky 47, Kyiv 03680, Ukraine


Large-scale perturbations – perturbations with low mode numbers (m and n) – often occur in toroidal

plasmas. The purpose of this work is to consider the influence of these perturbations on the transport of

the energetic ions. The results to be reported include those of Refs. [1,2] and can be summarized as

follows.

It is shown that the destabilization of Geodesic Acoustic modes (GAM and Energetic-particle-induced

GAM, i.e., E-GAM) by passing energetic ions in tokamaks can be accompanied with a considerable

energy transfer from these ions to the mode. This is the case when the mode is global and the plasma

density perturbation is large, which provides wave-particle interaction in a wide phase-space region. It is

found that the mode-induced slowing down of the energetic ions leads to a radial shift outwards / inwards

of the ions moving in the direction counter- / co- to the plasma current, in spite of the fact that the

canonical angular momentum of the particles is conserved during GAMs. Limits of applicability of these

results and some consequences of the considered transport are discussed.

The energetic-ion transport caused by radial displacements of particle resonances (“bucket transport”)

due to the collisional slowing down of the ions and / or the temporal evolution of the magnetic

configuration is considered. It is found that in these cases the problem can be reduced to analysis of the

Hamiltonian introduced in [3] (where the transport caused by the frequency chirping was studied). It is

concluded that regardless of the direction of the bucket motion, the total flux (involving both resonant

and non-resonant particles) is always directed against the gradient of fast-ion density. The bucket

transport may be of importance in the hybrid operation mode and in reversed-shear discharges. The

analysis carried out deals with zero-frequency perturbations; in addition, the 0 case is discussed.

The work is partly supported by the STCU-NASU project No. 6058 and NASU the Project No. 0114U000678.

[1] Ya.I. Kolesnichenko, V.V. Lutsenko, B.S. Lepiavko, Phys. Lett. A 378 (2014) 2683.

[2] Yu.V. Yakovenko, O.S. Burdo, Ya.I. Kolesnichenko, M.H. Tyshchenko, Phys. Lett. A, submitted.

[3] C. T. Hsu, C. Z. Chang, P. Helander, D. J. Sigmar, R. White, Phys. Rev. Lett. 72 (1994) 2503.

50

P-3: tae induced alpha particle and energy transport in iter

K. Schoepf, E. Reiter, T. Gassner

Institute for Theoretical Physics, University of Innsbruck, Austria (fusion@oeaw)


Mechanisms relevant to fast-ion transport in tokamaks are investigated and numerically modelled for a

qualitative as well as quantitative evaluation of their effects. In this context the Fokker-Planck code

FIDIT is used to describe the convective-diffusive transport, and the non-linear perturbative particle-in-

cell code HAGIS is employed to simulate self-consistently the interaction of energetic particles and

MHD waves. Properly switched upon checking stability/instability criteria, the iterative running

sequence of these codes enables the study of combined transport effects, e.g. the convective-diffusive

loss of energetic ions that are redistributed by waves. The iterative HAGIS/FIDIT coupling renders

possible a longer-time simulation of the transport behavior of fast ions in plasmas with MHD mode

activity. Referring to ITER scenario 2 (standard H-mode) with a constant DT fusion source we

considered the presence of 15 TAE modes and evaluated synergetic transport effects caused by the co-

action of wave-particle interplay and classical particle transport. As expected, a rapid loss of high-

energetic fusion alphas became evident. When the fast ion pressure reached a high enough value for

driving TAEs to significant amplitudes, a corresponding outward redistribution and loss of fusion born

alphas was demonstrated. Following this redistribution a substantial transport of precedently relocated

alphas was observed. Highly energetic alphas were shifted to the outer plasma edge in the wake of the

wave-particle interaction, where stronger convective-diffusive transport – further enhanced by the

magnetic field ripples – caused the loss of a significant portion of fast ions. Following the loss by

redistribution through interaction with TAEs, an additional decrease in particle number and energy is

observed, which results in a total loss of about 20% in particle number and energy content of fusion

alphas. While the alpha energy content increases quickly again, the total alpha particle number is still

decreasing until about 100 ms after the redistribution. Thus one can deduce that the alphas with highest

energy are removed first from the plasma due to ripple-enhanced diffusion at the plasma edge. This

transport happens slower for particles with lower energies. Since the fusion source is active all the time

and new alphas with 3.5 MeV are continuously born, the alpha energy content increases earlier, as then

only redistributed alphas with lower energies are removed from the plasma.


51

P-4: beam ion susceptibility to loss in nstx-u plasmas

D. S. Darrow, E. D. Fredrickson, M. Podestà and R. White Princeton Plasma Physics Laboratory, Princeton, NJ 08543, USA

D. Liu University of California, Irvine, Irvine, CA 92697, USA


NSTX-U will operate with three additional neutral beam sources whose tangency radii of 1.1, 1.2, and

1.3 m are significantly larger than the 0.5, 0.6, and 0.7 m tangency radii of the neutral beams previously

used in NSTX. These latter beams will also be retained for NSTX-U. Here, we attempt to formulate an

estimate of the susceptibility of the beam ions from all the various sources to loss under a range of

NSTX-U plasma conditions. This estimation is based upon TRANSP calculations of beam ion

deposition in phase space, and the location of the FLR-corrected loss boundary in that phase space.

Since TAEs were a prominent driver of beam ion loss in NSTX, we incorporate their effects through the

following process: NOVA modeling of TAEs in the anticipated NSTX-U plasma conditions gives the

mode numbers frequencies and mode structures that are likely to occur. Using this information as inputs

to the guiding center ORBIT code, it is possible to find resonant surfaces in the same phase space along

which beam ions would be able to diffuse under the influence of the modes. The degree to which these

resonant surfaces intersect both the beam deposition volume and the orbit loss boundary should then give

a sense of the susceptibility of that beam population to loss from the plasma.

Work supported by U.S. DOE DE-AC0209CH11466, DE-FG02-06ER54867, and DE-FG03-02ER54681

52

P-5: fokker-planck model for collisional loss of fast-ions in

tokamaks

V. Yavorskij1,2

, V. Goloborod’ko1,2

, K. Schoepf1

1Institute for Theoretical Physics, University of Innsbruck, Austria (fusion@oeaw) 2Institute for Nuclear Research, Ukrainian Academy of Sciences, Kyiv, Ukraine


Modelling of the collisional loss of fast ions from tokamak plasmas is important from the point of view

of the impact of fusion alphas and NBI ions on plasma facing components as well as for the development

of diagnostics of fast ion losses [1, 2]. The present paper develops a Fokker-Planck approach for the

assessment of the distributions of collisional loss of fast ions as depending on the coordinates of the first

wall surface and on the velocities of lost ions. It extends former Fokker-Planck treatments of the poloidal

distributions of fast ion loss induced by Coulomb collisions [3-5] to an arbitrary shape of the first wall

and accounts for the effects of finite gyroradius. Based on this newly developed Fokker-Planck approach

the poloidal distribution of neoclassical loss of fusion alphas in ITER will be examined. It is pointed out

that the loss distributions obtained with the novel Fokker-Planck treatment will be useful for the

verification of Monte-Carlo models [6, 7] used for simulating fast ion loss from toroidal plasmas.

[1] FASOLI, A., et al., Nucl. Fusion 47 (2007) S264–S284

[2] KIPTILY V.G et al, Nucl.Fusion 65 (2009) 065030

[3] PUTVINSKII S.V., “Alpha Particles in Tokamaks”, in Rev. of Plasma Physics edited by B.B. Kadomtsev, vol.

18, Consultant Bureau, NY, 1993.

[4] YAVORSKIJ, V., et al., EPS 2012, paper P1.144

[5] YAVORSKIJ., V.A. et al., Nucl. Fusion 43, 1077 (2003)

[6] KURKI-SUONIO, T., et al., Nucl. Fusion 49 (2009) 095001

[7] SHINOHARA, K., et al., Nucl. Fusion 51 (2011) 063028


53

P-6: the effect of perturbed electric fields and atomic

processes on the redistribution of energetic particles

R. Farengo1, C. Clauser

2, I. Montellano

3, P. García-Martínez

2, H. Ferrari1

2, L. Lampugnani

2

1Comisión Nacional de Energía Atómica, Centro Atómico Bariloche, Bariloche, Argentina.

2CONICET, Bariloche, Argentina.

3Instituto Balseiro, Bariloche, Argentina.

The effect of the electric field due to mode rotation on the redistribution of high energy ions is studied. Two

different scenarios are considered: α particles in an ITER like device and beam ions in an ASDEX-U like tokamak.

We have already shown [1] that the perturbed electric field (E1) can have a large effect on the redistribution of α

particles. Additional results, comparing different methods of calculating E1 will be presented. In recent numerical

studies of the effect of (2,1) modes on the redistribution of beam ions [2,3] the use of a static magnetic perturbation

is justified by noting that the transit frequencies of the ions are much higher than the mode frequency. We show that

trapped particles, which have a bounce frequency lower than the toroidal transit frequency, can be significantly

affected by the E1. Fig. 1 shows the effect of E1 on an 80 keV trapped ion for the conditions reported in [2] (two

mode periods shown). This could explain the large peak in ion losses at a 45° pitch (trapped particles) seen in the

experiments and not reproduced in the simulations [2].

Various mechanisms for anomalous α particle diffusion have been considered: large scale MHD fluctuations,

microturbulence and toroidal ripple. We show that processes that change the charge of the α particles can also

produce significant diffusion. Initial results show that for typical plasma parameters (n=1014 cm-3, T=10 keV) and

a 1% neutral density, a 1 MeV α particle diffuses much faster due to charge exchange processes than to classical

collisions. This effect will be important near the plasma edge and in the SOL, and should therefore be included in

calculations of the alpha particle flux reaching the wall or divertor plates.

Fig. 1. (a) Unperturbed orbit. (b) With a static magnetic perturbation. (c) With perturbed electric

and magnetic fields.

[1] R. Farengo, H. E. Ferrari,P.L. Garcia-Martinez, M.-C. Firpo, W. Ettoumi and A. F. Lifschitz. Phys. Plasmas

21, 082512 (2014).

[2] M. García-Muñoz, P. Martin, H.-U. Fahrbach, M. Gobbin, S. Günter, M. Maraschek, L. Marrelli, H. Zohm

and the ASDEX Upgrade Team. Nucl. Fusion 47, L10 (2007).

[3] E Strumberger1, S Günter, E Schwarz, C Tichmann and the ASDEX Upgrade Team. N. Jour. of Phys. 10,

023017 (2008).

54

P-7: studies of fast ion losses caused by mhd instabilities by using

faraday cup type lost ion probe in heliotron j plasmas

S. Yamamoto1, T. Sano

2, Y. Nakayama

2, K. Ogawa

3,4, M. Isobe

3,4, S. Kobayashi

1, T. Mizuuchi

1,

K. Nagasaki1, H. Okada

1, T. Minami

1, S. Kado

1, S. Ohshima

1, Y. Nakamura

2, S. Konoshima

1, L. Zang

1,

G.M. Weir1, N. Kenmochi

2, Y. Ohtani

2 and F. Sano

1

1Institute of Advanced Energy, Kyoto University, Gokasho, Uji 611-0011, Japan

2Graduate School of Energy Science, Kyoto University, Gokasho, Uji 611-0011, Japan

3National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan

4SOKENDAI (The Graduate University for Advanced Studies), Toki 509-5292, Japan


For the purpose of clarification on a mechanism of interplay between fast ions and fast ion

driven MHD instabilities, we have developed a Faraday cup type lost ion probe (FLIP) in

Heliotron J, which is the medium size (R ~ 1.2 m/<a> < 0.2 m) Stellarator/Heliotron and has

low magnetic shear in a whole plasma region. The FLIP is composed of eight thin aluminium

plates as electrode and can detect lost ions having energy of E = 2 ~ 45 keV for hydrogen and

pitch angle of χ = 90 ~ 150 deg. corresponding to co-going ions, respectively.

Energetic particle modes (EPMs) and/or global Alfvén eigenmodes (GAEs) are observed in the

Heliotron J plasmas which are heated by tangential co- and counter- injection of NB with energy

of Einj < 27 keV. The increases in lost ion flux synchronized with the bursting EPMs, which

have intense magnetic fluctuation and frequency chirping up and/or down, are observed in the

two electrodes with E = 20 ~ 45 keV/= 100 ~ 114 deg. and E = 2 ~ 12 keV/χ = 90 ~ 120 deg..

Full orbit calculation indicates that the detected ions should originate from plasma peripheral

region where the observed EPMs are locally excited. Amount of lost ion flux is proportional to

magnetic fluctuation amplitude of the EPMs. These results show that convective loss of ion is

induced by EPMs in NBI-heated Heliotron J plasmas.

55

P-8: simulation study of triton confinement and nuclear reaction

in the deuterium plasma experiment at lhd

M. Homma, S. Muramkami, M.Isobe1,H. Tomita

2 and K. Ogawa

1

Department of Nuclear Engineering, Kyoto University 1National Institute for Fusion Science

2Department of Quantum Engineering, Nagoya University


Deuterium plasma experiment campaign from 2017 is planned in the Large Helical Device (LHD). In

deuterium discharges, tritons (1.01 MeV) and neutrons (2.45 MeV) are produced by fusion reactions

between deuterium Neutral Beam Injection (NBI) beams and deuterium thermal ions. Understanding the

behavior of energetic tritons would make it possible to experimentally study energetic particle

confinement in future reactors. These experiments have been performed in JT-60U [1] known as triton

burn-up experiments.

In this study, confinement of energetic tritons for the LHD deuterium plasma is investigated using the

GNET (Global NEoclassical Transport) code [2], in which the drift kinetic equation (DKE) of energetic

particles is solved in five-dimensional phase space. GNET is also applied to evaluate the source profile

of the tritons solving the DKE for NBI beam ions. The velocity distributions of energetic tritons are

evaluated over a range of minor radii, and we present the characteristics of the triton distribution in

velocity space. Next, we calculate D-T nuclear reaction rates using the obtained velocity distribution of

tritons and simulate the signals of the neutron measurement systems in the D-D experiments on LHD.

[1] T. Nishitani et al., Plasma Phys. Control. Fusion 38, 355 (1996).

[2] S. Murakami et al., Nucl. Fusion 40, 693 (2000).

56

P-9: effect of high-z impurity on the nbi beam ion distribution and

heat deposition in the lhd plasma

H. Yamaguchi and S. Murakami

Department of Nuclear Engineering, Kyoto University, Kyoto, Japan


In the Large Helical Device (LHD) the high ion temperature is obtained by the carbon pellet injection[1]

and high ion temperature experiments have been performed with the neon and argon gas puffing [2]. In

high-Z plasmas, heat deposition of NBI heating per ion is expected to be larger than in pure hydrogen

plasma because of high Zi2/Ai of impurity ions and lower ion density. On the other hand, pitch-angle

scatterings with high-Z impurity ion can degrade the confinement of NB-born fast ions. In order to

elucidate effect of impurity seeding in NBI heating in LHD plasmas, NBI heating analysis taking into

account complex drift orbit and collisions with impurity ions is necessary. However, detailed analysis of

fast ion confinement and heat deposition of NBI heating in such high-Z plasmas of LHD is still not yet

done. In this study, we perform NBI heating simulations in high-Z impurity plasmas of LHD, using

the GNET code [3] based on Monte Carlo method. We solve a drift kinetic equation for NB-born fast

ions in five-dimensional phase space, taking into account pitch-angle- and energy scatterings as well as

energy slow down. Complex guiding-center motion in the three dimensional magnetic configuration of

LHD is followed in Boozer coordinates. We examine fast ion birth, confinement and heat depositions in

high-Z plasma of LHD and discuss the effect of high-Z impurities on the NBI beam ion distribution and

heat depositions in LHD

plasmas.

[1] H. Takahashi et al., Nucl. Fusion 53, 073034 (2013)

[2] Y. Takeiri et al., Nucl. Fusion 47 (2007) 1078–1085

[3] S. Murakami et al., Nucl. Fusion 40 ,693 (2000)

57

P-10: development of nonlinear collision operator for the

monte carlo simulation code in toroidal plasmas

S. Murakami , Y. Masaoka, H. Yamaguchi, M. Homma and A. Fukuyama

Department of Nuclear Eng., Kyoto Univ., Nishikyo Kyoto 615-8540, Japan


In a D-T fusion plasma α-particles (E =3.5MeV) are generated by the fusion reaction and those

α-particles mainly collide only with electrons because of very high velocity compared to the thermal ion

ones. Thus it is considered that the pitch angle scattering is very small for the α-particle during the

energy slow down. On the other hand, if we consider the relative velocity between the α -particles this

relative velocity sometimes becomes very small. In this case they would experience an additional pitch

angle scattering. Although the density of high-energy particle is much less than that of thermal other

ions, the collisions between α-particles would have some effect on pitch angle scattering.

This nonlinear collision effect may lead to deteriorate the α-particle confinement, because of increase of

pitch angle scatterings. Thus, the analysis including the both complicated orbit and the nonlinear

collisions are necessary to make clear the α-particle confinement in toroidal plasmas. However, the

nonlinear collision operator has not yet been formulated for the orbit following type of Monte Carlo

code.

We have developed the nonlinear collision operator, which can be easily implemented to the for the

Monte Carlo simulation code such as GNET [1,2]. In the previous papers [3,4] we have formulated the

nonlinear collision operator and have shown that the newly developed nonlinear collision operator

becomes the same formulation when we assume a Maxwellian background plasma. In this study we

benchmark our collision operator model with the Fokker-Planck code, TASK/FP. TASK/FP include the

nonlinear collision operator but the finite orbit effect cannot be included. So we benchmark the nonlinear

collision operator assuming no orbit effect. Then we will study the effect of nonlinear collisions on the

energetic particles confinement assuming a simple tokamak configuration.

[1] S. Murakami et al., Nucl. Fusion 40, 693 (2000).

[2] S. Murakami, et al. Nucl. Fusion 46, S245 (2006).

[3] Y. Masaoka and S. Murakami, Plasma Fusion Res. 8, 2403106 (2013).

[4] S. Murakami et al., Proc. 41st EPS Conf. Plasma Phys. 2014, Berlin, P4.013 (2014).

58

P-11: numerical and experimental study of the redistribution of

energetic and impurity ions by sawteeth in asdex upgrade

experiments

F. Jaulmes

1, B. Geiger

2, T. Odstrčil

2, M. Weiland

2, M. Salewski

3, A.S. Jacobsen

3, E. Westerhof

1 and the

ASDEX Upgrade team

1FOM Institute DIFFER – Dutch Institute For Fundamental Energy Research, The Netherlands

2Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany

3Technical University of Denmark, Department of Physics, Dk-2800 Kgs. Lyngby, Denmark


During sawtooth crashes, fast ions are redistributed according to a complex motion with respect to

the dynamics of the perturbed electromagnetic fields [1]. We discuss here the modelling of the

sawtooth reconnection as well as the trajectories of the ions: an experimental validation of the

modelling is given according to results from the ASDEX Upgrade experiment.

The array of the soft-X-ray diodes in ASDEX Upgrade allows for a good time-resolved tomographic

measurement of radiation emission during the sawtooth crash. Correspondingly, applying the

odelling of the sawtooth to a population of thermal tungsten impurity ions allows for the

reconstruction of the tungsten density evolution during the sawtooth crash. This reconstruction is in

turn compared with the tomographic reconstruction of the soft-X-ray.

Having assessed the dynamics of the sawtooth crash modelling on thermal tungsten ions give

confidence to apply it to the fast ions: we thus simulate a population representative of a realistic

Neutral Beam Injection (NBI) ions distribution in the geometry of the ASDEX Upgrade tokamak.

The initial spread of the NBI ions is provided first according to TRANSP simulations and also by

qualitatively trying to match tomographic data from the complete FIDA system. The validation of

our orbit-following code EBdyna_go [1] is done by comparing the experimental signals from the

Fast Ion D-Alpha diagnostic (FIDA) with simulated signals from the post-crash simulations. Further

we compare the FIDA velocity-space tomographies in the plasma center with the EBdyna_go

simulations before and after a sawtooth crash.

The resulting comparison yields a good agreement between the simulation and the experimental

data. In particular, a stronger redistribution of the higher-energy passing NBI ions is observed. This

is encouraging for further comparison in dedicated experiments that will in turn study the peculiar

effect of the sawtooth on populations of fast trapped ions such as the one generated by Ion Cyclotron

Resonance Heating systems.

References [1] F. Jaulmes, E Westerhof and H. J. de Blank, Nuclear Fusion 54 (2014), volume 10, 104

59

P-12: effect of the european design of tbms on iter wall loads

due to fast ions in the baseline (15MA), hybrid (12.5MA),

steady-state (9MA) and half-field (7.5MA) scenarios

T. Kurki-Suonio1, S. Äkäslompolo

1, K. Särkimäki

1, S. Sipilä

1, J. Varje

1 O. Asunta

1, and M. Gagliardi

2


2 F4E, Barcelona, Spain

The new physics introduced by ITER operation, of which there is very little prior experience, is related to

the very energetic (3.5 MeV) alpha particles produced in large quantities in fusion reactions. These

particles not only constitute a massive energy source inside the plasma, but also present a potential

hazard to the material structures that provide the containment of the burning plasma. In addition, the

negative neutral beam injection (NBI) produces 1 MeV deuterons which have to be well confined to

ensure successful operation of ITER.

The almost perfect confinement of energetic ions, predicted for axisymmetric tokamak configurations,

can be compromised by a variety of components breaking the axisymmetry: the finite number and

limited toroidal extent of the toroidal field (TF) coils (18 in ITER) cause a periodic magnetic field

perturbation with a magnitude exceeding 1% at the separatrix. This magnetic ripple can cause significant

fast particle leakage, leading to localized power loads on the walls. Therefore, ferromagnetic inserts (FI)

will be embedded in the double wall structure of the ITER vacuum vessel, reducing the ripple to 0.6%

everywhere else except near the NBI ports, where the ports interfere with the FI structures. The ITER

magnetic field at the edge is further perturbed by the test blanket modules (TBM), made of ferromagnetic

material and installed to test tritium breeding. TBMs cause poloidally and toroidally localized

perturbations to the magnetic field. Consequently, the ITER field structure at the edge is quite complex,

and studying its effect on fast ion confinement analytically is impossible.

In this contribution, we calculated the ITER 3D magnetic field including the effects of the ferritic

components (FIs and TBMs). The components were modelled with unprecented detail as energetic ions

are very sensitive to magnetic field structure and, therefore, even small details in the field could have a

significant effect on fast ion losses. The FEM solver COMSOL was used to first calculate the

magnetization of the ferromagnetic components due to plasma current and currents flowing in the field

coils. The perturbation field due to the magnetization was then calculated and added to the unperturbed

field integrated from the coils using the Biot-Savart law.

We simulate the fast ion wall power loads using the Monte Carlo orbit-following code ASCOT in the full

3D magnetic configuration. The first wall model also has full 3D features. The simulations are carried

out for all the foreseen operating scenarios of ITER: the baseline 15 MA standard H-mode operation, the

12.5 MA hybrid scenario, the 9 MA advanced scenario, and the half-field scenario with helium plasma

that will be ITER’s initial operating scenario. Both thermonuclear fusion alphas and NBI ions from ITER

heating beams are addressed. The alpha population is generated according to the fusion reactivity, given

by the density and temperature profiles corresponding to the stationary phases of the ITER plasmas,

while the NBI population is generated from beamlets that correspond to the injector’s geometry. The

ferritic components are found not to jeopardize the integrity of the first wall, but application of NBI in

the ramp-up phases can lead to unacceptable shine-through.

60

P-13: comparison of fast ion confinement during on-axis and

off-axis neutral beam experiments on nstx-u

D. Liu,W. W. Heidbrink, G.Z. Hao University of California, Irvine, Irvine, CA 92697, USA

M. Podesta, D. S. Darrow, E. D. Fredrickson, and S. S. Medley

Princeton Plasma Physics Laboratory, Princeton, NJ 08543, USA

A second more tangential neutral beam injector (NBI) is a major upgrade component of the National

Spherical Torus Experiment – Upgrade (NSTX-U) facility with the purpose of improving NBI current

drive efficiency and providing more flexibility in the control of current and pressure profile. Good fast-

ion confinement is essential to achieve the anticipated improvements in performance. After the

completion of upgrade construction of NSTX-U this summer, a “sanity check” experiment will be

performed to characterize the confinement and fast ion distribution function produced by this new off-

axis and the existing on-axis NBI lines, and to compare them with classical predictions through

NUBEAM modeling. In the “sanity check” experiment, various short (~20ms) and relatively long

(~90ms) neutral beam pulses from different on-axis and off-axis neutral beam sources will be injected

into quiescent L-mode discharges, which are optimized for accurate neutron, Fast-Ion D-Alapha (FIDA)

and Solid State Neutral Particle Analyzer (SSNPA) measurements. The neutron rate decay after the turn-

off of short neutral beam pulses will be used to estimate the fast ion confinement time and to investigate

its dependence on neutral beam source/geometry, injection beam energy, plasma current and magnetic

field. A slowing-down fast ion distribution and spatial profile during the injection of relatively long

neutral beam pulses will be measured with FIDA and SSNPA diagnostics and compared with classical

predictions through NUBEAM and FIDAsim modeling. Also, fast ion prompt losses in all conditions

will be monitored with a scintillator Fast Lost Ion Probe (sFLIP) diagnostic. The experimental

techniques, measurements of fast ion confinement and distribution function during on-axis and off-axis

neutral beam experiments, and comparisons with NUBEAM modeling will be presented in detail.

Work supported by U.S. DOE DE-AC0209CH11466, DE-FG02-06ER54867, and DE-FG03-02ER54681

61

P-14: numerical investigation of fast ion losses induced by

resonant magnetic perturbations and edge localized modes at

asdex upgrade

M. Nocente1, M. Garcia-Munoz

2,3, N. Lazanyi

4, M. Dunne

3, J. Galdon-Quiroga

2, M. Hoelzl

3,

M. Rodriguez-Ramos2, L. Sanchis-Sanchez

2, E. Strumberger

3, WP15-ER/IPP-05 Contributors and the

ASDEX Upgrade Team

1Dipartimento di Fisica “G. Occhialini”, Università degli Studi di Milano-Bicocca,Piazza della Scienza 3, 20126,

Milano, Italy 2

Department of Atomic, Molecular and Nuclear Physics. University of Sevilla. Spain 3Max-Planck-Institut für Plasmaphysik, Garching, Germany

4BME NTI, Pf 91, H-1521 Budapest, Hungary


A recent addition to the field of investigation on Edge Localised Modes (ELMs) has been the observation

that fast ion losses can occur even when the ELMs are mitigated by means of resonant magnetic

perturbations (RMPs) [1]. Such additional losses of energetic particles represent an added threat for

machine protection and need to be understood and, eventually, controlled.

In this contribution we present the results of a numerical study aimed at unveiling the principle

mechanisms responsible for the observed losses at ASDEX Upgrade. Collisionless simulations of the

beam ion orbits in a realistic three-dimensional, perturbed magnetic equilibrium were performed by

means of the GOURDON code. In the presence of RMPs, these were used especially to calculate

geometrical resonances between the orbital frequencies of the beam ions and to evaluate their role in the

loss mechanism. A class of trapped particles exploring the entire pedestal and scrape off layer is found to

satisfy geometrical resonance conditions. Compared to non resonant particles, ions fulfilling geometrical

resonances can experience increased losses, but also - quite surprisingly - enhanced confinement,

depending on their toroidal turning point location. Starting from these results, calculations of fast ion

losses in the case of a rigid or differential rotation of the RMPs to mitigate first wall heat loads are

presented and compared to recent experimental findings [2].

In the case of unmitigated ELMs, realistic JOREK [3] calculations of the magnetic equilibrium of a full

ELM cycle were used as input for the simulations. Similarly to experiment, GOURDON results show a

filamentary temporal pattern for the losses, with maxima corresponding to characteristic structures

appearing beyond the last closed flux surface of the magnetic equilibria. Unlike experiment [2],

however, the predicted phase space structure of the unconfined ions does not show particles at pitch

angles different from those observed in the case of prompt losses. Motivations behind such discrepancy

are illustrated and possibilities for simulation improvements are discussed.

[1] M. Garcia-Munoz et al. 2013 Nucl. Fusion 53 123008 [2] Lazanyi N. et al. this meeting [3] Hölzl M. et al. 2012

Phys. Plasmas 19 082505


62

P-15: Pressure anisotropy and flow suppress diamagnetic holes

in high-beta tokamaks

B. Layden,1, M. J. Hole,

1 and R. Ridden-Harper

2

1 Research School of Physics and Engineering, The Australian National University, Acton ACT 2601, Australia

2 Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch 8140, New

Zealand


Increasingly high beta values are being obtained in modern high-performance tokamaks, with the

Component Test Facility and Spherical Tokamak Power Plant concept devices projected to achieve

volume-averaged toroidal betas of 30% and 60% respectively. At still higher beta, such that 𝛽𝑞2 ≫ 𝜀2

where 𝜀 is the inverse aspect ratio, analytical studies have shown that fundamental changes to the

equilibria occur, the most striking for static equilibria being the formation of a field-free region called a

diamagnetic hole. In recent work, Fitzgerald et al. (2011) showed that sufficiently high toroidal flow

speeds (𝑢 ≥ 𝑢𝑐) suppress the diamagnetic hole. Such flows can be induced by auxiliary heating

processes such as neutral-beam injection (NBI), which also generate significant pressure anisotropy.

However, the effect of pressure anisotropy (and its combined effect with flow) on high-beta equilibria

had not been investigated. We extend the work of Fitzgerald et al. to include both toroidal flow and

pressure anisotropy. The force-balance model is based on guiding-centre plasma theory for a bi-

Maxwellian distribution and the ideal MHD Ohm’s law. We find that pressure anisotropy with 𝑝∥ > 𝑝⊥

(𝑝∥ < 𝑝⊥) reduces (enhances) the plasma diamagnetism relative to the isotropic case whenever an

equilibrium solution exists, which occurs if and only if the firehose (mirror) stability criterion is satisfied.

We find that all firehose-stable solutions for 𝑝∥ > 𝑝⊥ suppress the diamagnetic hole. For the no-flow case

studied, plasmas with 𝑝∥/𝑝⊥ > 𝛼1 = 1.01 are firehose stable. The stability threshold 𝛼1 decreases with

increasing toroidal flow, and above the flow threshold 𝑢𝑐 we find 𝛼1 = 0, so that all 𝑝∥ > 𝑝⊥ equilibria

are firehose stable. Parallel heating processes such as tangentially-oriented NBI are thus highly effective

in suppressing the diamagnetic hole. On the other hand, for 𝑝∥ < 𝑝⊥ there are no mirror-stable solutions

below the flow threshold 𝑢𝑐. Above this flow speed (where the diamagnetic hole no longer exists in the

isotropic case), mirror-stable solutions exist for 𝑝∥/𝑝⊥ > 𝛼2, where 𝛼2 decreases from unity with

increasing flow above threshold. Toroidal flow therefore improves mirror-stability for high-beta plasmas

with perpendicular heating such as perpendicularly-oriented NBI and ICRH.

63

P-16: investigation of fast ion behavior using orbit following

monte-carlo code in magnetic perturbed field in kstar

Kouji Shinoharaa1, Junghee Kim

2,3, Jun Young Kim

3, YoungMu Jeon

2, and Yasuhiro Suzuki

4

1Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan

2National Fusion Research Institute, Daejeon, Korea

3University of Science and Technology, Daejeon, Korea

4National Institute for Fusion Science, Toki, Gifu, Japan

Email Address of Submitting author: [email protected]

The effect of the ELM coil field in the ITER on fast ions was studied by using the OFMC code [1]. The

studies revealed that ELM coil field could deteriorate fast ion confinement or increase heat load on the

divertor and its non-heat-resistance components. The studies were based on the calculation using the so-

called “vacuum field”, which was produced by the ELM coil alone. However, it is considered that the

externally applied ELM coil field could be affected by the plasma response. In the perturbed filed

affected by the plasma response, the knowledge on fast ion behavior is limited to specific cases. It is

interesting to know how the plasma response changes the perturbed field and its effect on fast ion

behavior. One of the important fast ion responses to be investigated is the heat load, especially localized

heat load, on plasma facing components (PFCs). The heat load studies indicated the 3D dependence of

the heat load on the 3D shape of PFCs as well as the 3D nature of a magnetic field [2].

In this presentation, as case studies, we compare the fast ion behavior and heat load on the PFCs in

various magnetic field, including the case where the plasma response is taken into account, in an actual

geometry using the KSTAR device. The magnetic field with the plasma response is calculated by using

HINT2 code [3]. The change in magnetic field structure was observed depending on the kinetic plasma

profile. The heat load distribution was changed responding to the change in the field structure. This

suggests the predicition of heat load in the RMP experiments in ITER is not easy since the magnetic field

perturbation depends on plasma parameters in a discharge. The protection of the non-heat-resistance

components is recommended in ITER. The heat load in the divertor region is not large in the case of

KSTAR in contrast to ITER. The most loss particles hit the limiter structure. We will report the results of

the calculations.

[1] Tani K., et.al. , NF 52 (2012) 013012; Shinohara K., et.al., NF 52 (2012) 094008;

Oikawa T., et.al., in Proceedings of the 24th IAEA Fusion Energy Conference (2012)

[2] Shinohara K., et.al., NF 43 (2003) 586; M. Garcia-Munoz, et.al., PPCF 55 (2013)

124014; M. A. Van Zeeland et al., PPCF 56, (2014) 015009

[3] Suzuki Y., et al., NF 46 (2006) L19


64

P-17: fast particle physics and its connection to

performance on c-2

N.G. Bolte, M.W. Binderbauer, T. Tajima, A. Smirnov, R. Clary, B.H. Deng, H. Gota, D. Gupta,

S. Korepanov, R. Magee, M. Thompson, E. Trask, M. Tuszewski, K. Zhai

Tri Alpha Energy, Inc.


Conventional field-reversed configurations (FRCs)—high-beta, prolate compact-toroids embedded in

poloidal magnetic fields—face notable stability and confinement concerns. These can be ameliorated by

various control techniques, such as introducing a significant fast-ion population. Indeed, adding neutral

beam injection into the FRC over the past half-decade has contributed to striking improvements in

confinement and stability. Neutrons studies show that superthermal ions slow down and diffuse

classically. Fast-ion pressure is shown to increase in time and with increased neutral-beam power and

becomes equal to thermal plasma pressure under full beam power. Further, the addition of electrically

biased plasma guns at the ends, magnetic end-plugs, and advanced surface conditioning leads to a

dramatic reduction in losses and greatly improves stability. The n=2 mode is shown to be significantly

reduced with increasing neutral-beam power and/or increased plasma gun voltage. Broadband magnetic

fluctuations also decrease with increasing beam power. All together, these factors enable the build-up of

a well-confined and dominant fast-ion population. Under such conditions, highly reproducible,

macroscopically-stable and hot FRCs (with total plasma temperature of ~ 1 keV) with record lifetimes

are achieved. These accomplishments point to the prospect of advanced, beam-driven FRCs as an

intriguing path toward fusion reactors.

65

P-18: fishbone activity in east neutron beam injection plasma

Liqing Xu1, Jizong Zhang

1, Kaiyun Chen

1, Liqun Hu

1, Erzhong Li

1, Shiyao Lin

1, Tonghui Shi

1,

Neng Pu1, Yanmin Duan

1, Yubao Zhu

2, Xiuli Sheng

1 and Jinlong Zhao

1

1Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China

2Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA

Repetitive fishbones near the trapped ion processional frequency was observed for the first time in the

neutron beam injection (NBI) high confinement plasmas in EAST tokamak，diagnosed using a newly

developed compact silicon photodiode based solid state neutral particle analyzers (ssNPA) together with

an upgraded high spatial-temporal-resolution multi-arrays soft x-ray (SX) system. This 1/1 typical

internal kink mode travels with a rotation speed faster than the bulk plasma in the plasma frame. This

mode frequency shows the nature of typical frequency chirping down, as evidenced by SX

measurements. It is found that this ion fishbone can trigger core sawtooth crash, multiply with edge 2/1

sideband mode as well as lead to a fishbone-long lived saturated kink mode (LLM)-fishbone transition.

Furthermore, by means of SX tomography, a correlation between the mode amplitude and the mode

frequency was found.

Typical frequency whistling down spectrograms of fishbone as observed from a central SX channel

together with the central bulk plasma rotation speed (blue star) measured by x-ray crystal spectrometer.

Time/s

Fre

quency (

kH

z)

4.67 4.675 4.68 4.685 4.69 4.695 4.7 4.705 4.71 4.715 4.72

12

13

14

15

16

17

18

19

20

21

22

ArXVII,q=1

Core SX @ 48605

f 4kHz

ffb

(1.75-5.75) 1.25 kHz

66

P-19: progress in gyrokinetic particle simulation of Alfvén

instabilities

Z. Lin University of California, Irvine, California 92697, USA

This paper reports recent progress in global gyrokinetic particle simulation of Alfven instabilities excited by

energetic particles (EP) in fusion plasmas, in particular, the nonlinear saturation of toroidal Alfven eigenmode

(TAE) by zonal fields and the excitation of beta-induced Alfven-acoustic eigenmode (BAAE) by EP.

TAE saturation by zonal fields-- GTC simulations1,2

of TAE in DIII-D shot #142111 near 525ms have been

extended to nonlinear regime to test effects of EP nonlinearity, thermal plasma nonlinearity, and zonal fields (zonal

flow and zonal current). When only EP nonlinearly is kept in the simulation (green line in figure), TAE saturates at

a high amplitude due to the relaxation of EP density profiles. When thermal plasma nonlinearity is added in the

simulation (red line), TAE saturates at a lower amplitude, indicating the importance of the thermal plasma

nonlinearity. Finally, when zonal fields are self-consistently kept in the simulation (blue line), TAE saturates at a

much lower amplitude and there is little relaxation in EP density profiles. The TAE mode structures are

somewhat distorted by the zonal flow. The effects

of zonal fields are mostly by the zonal flow, similar

effects are observed in the nonlinear saturation of

beta-induced Alfven eigenmode (BAE)3.

Suppressing zonal current causes little difference in

the TAE saturation amplitude. The collisionless skin

depth effects likely suppress the modulational

instability. The zonal field generation is thus via

mode coupling, similar to earlier MHD-gyrokinetic

simulations. The growth rate of zonal fields is

slightly less than twice of TAE growth rate,

indicating some damping of the zonal fields by

thermal plasmas.

BAAE excitation by EP -- The existence of BAAE

in toroidal plasmas is verified by GTC simulations.

In the Ti≪Te limit, where the BAAE is weakly damped, the existence of BAAE is verified in simulations using

initial perturbation, antenna excitation, and energetic particle excitation, respectively. The damping rate of the

BAAE is comparable to the real frequency in simulations with more realistic Ti~Te for both reversed shear and

monotonic q profiles. Surprisingly, the BAAE can be easily excited by modest EP density gradient due to the

formation of the well-behaved eigenmode structure, which is very different from the singular structure of the

heavily damped quasimode. The BAAE mode structure in the reversed shear q profile has opposite triangle shape

compared to the monotonic q profile. The frequency sweeping of the BAAE is observed in the reversed shear q

profile, but not in the monotonic q profile. In collaboration with SciDAC GSEP Center and GTC Team.

1. Radial Localization of Toroidicity-Induced Alfven Eigenmodes, Zhixuan Wang, Zhihong Lin, Ihor Holod,

W. W. Heidbrink, Benjamin Tobias, Michael Van Zeeland, and M. E. Austin, Phys. Rev. Lett. 111,

145003 (2013).

2. Properties of Toroidal Alfven Eigenmode in DIII-D Plasma, Z. X. Wang, Z. Lin, W. J. Deng, I. Holod, W.

W. Heidbrink, Y. Xiao, H. S. Zhang, W. L. Zhang, M. A. Van Zeeland, Phys. Plasmas 22, 022509 (2015).

3. Nonlinear generation of zonal fields by the beta-induced Alfven eigenmode in tokamak, H. S. Zhang and

Z. Lin, Plasma Sci. Technol. 15, 969 (2013).

67

P-20: experimental investigation of elm-induced fast-ion losses at

the asdex upgrade tokamak

N. Lazányi1, M. Garcia-Muñoz

2,3,4, M.Nocente

5, J. Galdon-Quiroga

2, M. Hoelzl

4, G. Por1, P. Poloskei

1,

M. Rodriguez-Ramos2,3

, L. Sanchis-Sanchez2, G.I. Pokol

1, the EUROfusion MST1

Team and the ASDEX Upgrade Team4


2Dept. of Atomic, Molecular and Nuclear Physics. University of Sevilla. Spain

3CNA (U. Sevilla, CSIC, J. de Andalucia). Spain

4Max-Planck-Institute für Plasmaphysik, Garching, Germany

5Dipartimento di Fisica “G. Occhialini”, Università degli Studi di Milano-Bicocca,Piazza della

Scienza 3, 20126, Milano, Italy


Edge localized modes (ELMs) are inherent instabilities of H-mode plasmas and are observed causing

fast-ion losses [1]. The lost fast ions can be measured by a scintillator-based fast-ion loss detector (FILD)

[2], which works as a magnetic spectrometer and sorts the fast ions by their gyroradius and pitch angle

relative to the local magnetic field lines in front of the detector. The detectors are equipped with

CCD/CMOS cameras observing the whole scintillator (velocity-phase space) and photomultiplier tubes

(PMTs), which are integrating regions of the scintillator, but their high sampling rate makes them

capable to detect high frequency fluctuations in the losses.

An overview of the internal structure of the observed ELM-induced fast-ion losses is given, and the

losses have been analysed both in time domain and in velocity-space based on the signal of the PMTs

and camera images, respectively. The observed structures of the ELMinduced losses are qualitatively

compared to GOURDON simulation results using magnetic equilibria of a full ELM cycle provided by

the JOREK code [3]. The spatial structure of the modes corresponding to ELMs was also investigated.

Internal MHD perturbations such as Neoclassical Tearing Modes (NTMs) are observed to change the

measured ELM induced fast-ion losses. The counter-effect is also true with ELMs significantly affecting

the observed NTM induced losses with islands localized in the outer mid radius. The impact that the

interaction between ELMs and NTMs has on the temporal evolution of losses as well as on their

velocity-space will be presented and discussed in light of the JOREK-GOURDON simulations.

[1] M. GARCIA-MUNOZ et al., Plasma Phys. and Control. Fusion 55 (2013) 124014.

[2] M. GARCIA-MUNOZ et al., Rev. Sci. Instrum. 80 (2009) 053503.

[3] M. NOCENTE et al., same conference


68

P-21: analysis of icfr heating and icfr-driven fast ions in

recent jet experiments

M.J. Mantsinen1, C. Challis

2, J. Eriksson

3, D. Frigione

4, J. Garcia

5, C. Giroud

2, T. Hellsten

6,

A. Hjalmarsson3, D.B. King

2, E. Lerche

7, M. Schneider

5, S. Sharapov

2 and JET contributors*

EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, UK 1ICREA-Barcelona Supercomputing Center, Barcelona, Spain 2CCFE, Culham Science Centre, Abingdon, OX14 3DB, UK

3Uppsala University, Department of Physics and Astronomy, Sweden

4ENEA, Frascati, Italy

5CEA, IRFM, 13108 Saint-Paul-lez-Durance, France

6Dept. of Fusion Plasma Physics, EES, KTH, Stockholm, Sweden

7Laboratory for Plasma Physics, LPP-ERM/KMS, Brussels, Belgium

*See Appendix of F. Romanelli et al., Proc. 25th IAEA FEC 2014, Saint Petersburg, Russia

Email Address of Submitting author: [email protected]

Heating with waves in the ion cyclotron range of frequencies (ICRF) plays an important role in the

operation and the performance optimization of several present-day experimental fusion devices. ICRF

waves will also be used in ITER and are planned for the demonstration fusion power plant DEMO. For

ITER, the main ICRF scenario is second harmonic heating of tritium which coincides with the

fundamental minority heating of 3He. For second harmonic heating of tritium, as for other harmonic

ICRF heating schemes, the damping of the wave power is a finite Larmor radius effect. Therefore, its

physics can be studied in a non-activated environment in the present day experiments using ICRF

schemes involving second or high-harmonic damping.

In the present paper, recent experiments in JET with ICRF heating are analyzed with the time-dependent

ICRF modelling code PION [1] with special emphasis on the physics of higher harmonic ion cyclotron

damping in preparation of ITER. In particular, we consider three different ICRF heating scenarios where

second or higher harmonic damping has been observed to play an important role: (a) hydrogen minority

heating, coinciding with second harmonic heating of deuterium beam ions, in high-performance JET

hybrid discharges; (2) third harmonic heating of deuterium beam ions in experiments for fusion product

studies [2] and (3) second harmonic heating of hydrogen in hydrogen plasmas. The experimental results

are compared to modelling and overall, good agreement is found. This increases our confidence in the

modelling of higher-harmonic ICRF heating schemes and, in particular, in the extrapolations of the

performance of second harmonic ICRF heating of tritium in ITER and DEMO.

[1] L.G. Eriksson, et al. Nucl. Fusion 33 (1993) 1037.

[2] S. Sharapov et al., this conference.

69

P-22: a stability study of α-particle driven alfvén eigenmodes in

jet d-t plasmas

J. Ferreira1, D. Borba

1, R. Coelho

1, L. Fazendeiro

1, A.C.A. Figueiredo

1, N. F. Loureiro

1, F. Nabais

1,

P. Rodrigues1, J. Conboy

2, M. Fitzgerald

2, S.E. Sharapov

2, I. Voitsekhovitch

3, and JET Contributors

§

EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, UK 1Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa,

Portugal

2CCFE, Culham Science Centre, Abingdon OX14 3DB, United Kingdom,

3EuroFusion Consortium Programme Unit, Boltzmannstr. 2, D-85748, Garching, Germany,


Given the unique capabilities of the Joint European Torus (JET) a campaign with deuterium-tritium

(DT) plasmas is being planned in advance of ITER operations [1,2]. As a contribution to the

preparation efforts, a tool that has recently been developed for the systematic linear-stability

assessment of Alfvén eigenmodes in the presence of fusion born α-particles [3,4] is here applied to a

representative set of JET DT scenarios. This study will allow us to better understand the impact of α-

particles on Alfvén stability. Starting from a selected set of pulses [2] the equilibria and fast particle

distributions are predicted through transport modelling using the numerical transport code TRANSP

[5]. The Alfvén spectrum and its stability is computed using the ASPACK suite of codes [3,4], which

includes the equilibrium solver HELENA [6], the ideal magnetohydrodynamic eigensolver MISHKA

[7], and the linear-stability hybrid MHD/drift-kinetic numerical code CASTOR-K [8].

As a result of an extensive linear assessment of the growth rates for the Alfvén spectra of different DT

scenarios due to driving interaction with α-particles and damping on thermal populations, the most

unstable Alfvén eigenmodes are identified and their importance discussed. Other relevant mechanisms

such as radiative and continuum dampings are also tackled and estimates are given.

Acknowledgments IST activities received financial support from “Fundação para a Ciência e Tecnologia”

through project UID/FIS/50010/2013.

References [1] L. Horton and JET Contributors, 2015, 12

th International Symposium on Fusion Nuclear

Technology, ICC JEJU, Jejun Island Korea, oral presentation. [2] S.E. Sharapov, I. Voitsekhovitch, et al.,

2011, 38th

European Physical Society Conference on Plasma Physics, Strasbourg, France, P5.117. [3] P.

Rodrigues et al., 2015, “Systematic linear-stability assessment of Alfvén eigenmodes in the presence of

fusion α-particles for ITER-like equilibria”, submitted to Nuclear Fusion.

[4] P. Rodrigues et al., 2014, Proceedings of the 25th

IAEA Fusion Energy Conference, Saint Petersburg,

Russia, TH/P3-25, arXiv:1410.2744. [5] R. J. Goldston, D. C. McCune, et al., 1981, J. Comput. Phys. 43, p.

61. [6] G. Huysmans et al., 1991, Europhysics Conference on Computational Physics (World Scientific) p.

371. [7] A.B. Mikhailovskii et al., 1997, Plasma Phys. Rep. 23, p. 844. [8] D. Borba and W. Kerner, 1999, J.

Comput. Phys. 153, p. 101 – 138.

§See the Appendix of F. Romanelli et al., Proceedings of the 25th IAEA Fusion Energy Conference 2014,

Saint Petersburg, Russia

70

Poster Session II – Thursday 3rd September, 15.05 -17.15

P-23 P. Puglia The JET Upgraded Toridal Alfven Eigenmode diagnostic

system

P-24 M. Hole Developments in advanced MHD Spectroscopy

P-25 C. Ryu Particle in Cell Simulation of Toroidal Alfven

Eigenmodes in KSTAR

P-26 Z. Qu Flow enabled instabilities in energetic geodesic acoustic

modes (EGAMs)

P-27 Ph. Lauber Off-axis NBI-driven energetic particle modes at ASDEX

Upgrade

P-28 X. Du Resistive Interchange Mode destabilized by Helically

Trapped Energetic Ions in LHD plasma

P-29 V. Fusco Electron fishbone dynamic studies in tokamaks with the

XHMGC code

P-30 G. Fogaccia Linear benchmark between HYMAGYC and HMGC

codes

P-31 A. Stahl Kinetic modelling of runaway electron dynamic

P-32 J. Huang Fast-Ion D-Alpha Spectrum during EAST neutral-beam

heated plasmas

P-33 V. goloborod’ko Evaluation of fluxes of lost alphas for gamma-ray

diagnostics in ITER

P-34 V. Yavorskij Interpretive and predictive modelling of fluxes of charged

fusion products lost from tokamak plasmas P-35 A. Sanyasi Diagnosis of Mirror Trapped Particles and Excitation of

Energetic Particle (EP) Driven Modes in LVPD

P-36 M. Nocente Diagnosing MeV range deuterons with neutron and

gamma ray spectroscopy at JET

P-37 L. Stagner A comparison of reconstruction methods for inferring the

fast-ion distribution function from multiple FIDA

measurements

P-38 Y. Zhu Preliminary Results of the EAST Integrated Energetic

Neutral Particle Analyzer and Its Conceptual Design on

the HL-2A/M Tokamaks

71

P-39 S. Sharapov Fast Ion D-D and D-3He Fusion on JET

P-40 K. Nagaoka Measurement of Phase Space Structure of Fast Ions

Interacting with Alfven Eigenmodes

P-41 J. Galdon Damage of Plasma Facing Components due to Fast-Ion

Losses in the ASDEX Upgrade Tokamak

P-42 M. Weiland Further acceleration of beam ions by 2nd harmonic ion

cyclotron heating in ASDEX Upgrade

I-6 G. Fu Stability and Nonlinear Dynamics of Beam-driven

Instabilities in NSTX

I-7 A. Biancalani Non-perturbative nonlinear interplay of Alfven modes

and energetic ions

I-8 Y. Kazakov Fast Ion Generation with Novel Three-Ion ICRF

Scenarios: from JET, W7-X and ITER applications to

aneutronic fusion studies

I-9 X. Wang Structure of wave-particle interactions in nonlinear

Alfvénic fluctuation dynamics

I-10 A. Bierwage Alfven Acoustic Channel for Ion Energy in High-Beta

Tokamak Plasmas

I-11 M. Fitzgerald Predictive nonlinear studies of TAE-induced alpha-

particle transport in the Q=10 ITER baseline scenario

I-12 M. Cole Progress in non-linear electromagnetic gyrokinetic

simulations of Toroidal Alfvén Eigenmodes

72

P-23: the jet upgraded toridal alfven eigenmode diagnostic

system*

P. Puglia2, W. Pires de Sa

2, P. Blanchard

1, S. Dorling

4, S. Dowson

4, A. Fasoli

1, J. Figueiredo

5,

R. Galvão2, M. Graham

4, G. Jones

4, C. Perez von Thun

5, M. Porkolab

3, L. Ruchko

2, D. Testa

1,

P.Woskov3 and JET Contributors

6

EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, UK 1Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), CH-

1015 Lausanne, Switzerland 2Instituto de Física, Universidade de São Paulo, São Paulo CEP 05508-090; Brazil

3PSFC-MIT

4CCFE, Culham Science Centre, Abingdon OX14 3DB, United Kingdom

5EUROfusion PMU, Culham Science Centre, Abingdon, Oxon, OX 14 3DB United Kingdom

6See the Appendix of F. Romanelli et al., Proceedings of the 25th IAEA Fusion Energy Conference 2014, Saint

Petersburg, Russia


The JET Toroidal Alven Eigenmode (AE) diagnostic system is undergoing a major upgrade to provide a

state of the art excitation and real-time detection system for JET. Experimental measurements and studies

of AE at JET have been done successfully first with the saddle coil system [1] and then with purpose

built in-vessel antennas with real time mode tracking algorithm [2]. Complete new excitation and digital

control system have been developed for this upgrade and are currently installed to provide JET with a

unique diagnostic to study AE in DT experimental campaign and towards ITER.

New exciters consisting of 4kW class D power switching amplifiers, one for each antenna, have been

developed in collaboration with the industry to cover the frequency range of operation 10- 1000kHz with

RF pulse duration of 15s and repeatability <15min. Due to the varying transmission line impedance

throughout the frequency band, design solution with high resilience to reflected power was implemented

with VSWR>>10:1.

A complete new digital amplifier control system has been implemented based on FPGA modules for

amplifier frequency and phase control with frequency resolution <1Hz and phase<0.3 degrees at 100kHz.

Gain control along with timing, gating and trip management is done using RT LabView.

New capabilities like independent antenna current and phase control will allow improved excitation

control, better definition of antenna spectrum combined with enhanced system reliability.

[1] Fasoli A. et al 1995 Phys. Rev. Lett. 75 645;

[2] Testa D. et al 2004, Proc. 23rd Symp. on Fusion Technology

*This work has been carried out within the framework of the EUROfusion Consortium and has received funding


opinions expressed herein do not necessarily reflect those of the European Commission.” The Brazilian group

works under the Brazil – EURATOM collaboration agreement, with support from FAPESP Project 2011/50773-0.

The work of the US collaborators at MIT was supported by US DOE Grant DE-FG02-99ER54563. This work

was supported in part by the Swiss National Science Foundation.


73

Fig. 1: (a) Possible ion temperature

profiles (solid) with core temperature

matching crystallography data from

discharge #4229, and (b) corresponding

profile of ηi/ηic . In both panels the dashed

line corresponds to a possible Ohmic ion

temperature profile, with τ=Te/Ti taken

from discharge #4229 prior to NBI

heating. In (b) the light line is r of the

BAE.

P-24: Developments in advanced MHD Spectroscopy

M.J. Hole1, S. Cox

1, C. M. Ryu

2, M. H. Woo

3, K. Toi

4, J. Bak

3, S. Sharapov

5, M. Fitzgerald

1

1Plasma Theory and Modelling Group , Australian National University, ACT 0200, Australia

2 POSTECH, Pohang, Korea.

3 National Fusion Research Institute, Daejon, Korea

4 National Institute for Fusion Science, GIFU Prefecture, Japan

5 EURATOM/CCFE Fusion Assoc., Culham Science Centre, Abingdon, Oxon OX14 3DB, UK

[email protected]

We report on a range of wave activity observed during neutral beam heating in KSTAR plasmas,

including BAE’s, TAE’s, and ion fishbones. A detailed analysis of 40 kHz magnetic fluctuations with a

toroidal mode number of n = 1 reveals a BAE resonant with the q = 1 surface. [1]. For this case, we have

computed the threshold to marginal stability for a range of ion temperature profiles. These suggest the

BAE can be driven unstable by energetic ions when the ion temperature radial gradient is sufficiently

large. Figure 1 shows candidate ion temperature profiles with core temperature matching

crystallography data from neighbouring discharge #4229, as well as the corresponding profile of ηi/ηic ,

where is ηic is the critical value of ηi = (∂ ln Ti/∂ ln ni) necessary for ion thermal excitation. For

sufficiently high radial temperature gradient and/or sufficiently high ion temperature, the Alfvénic ion

temperature gradient driven mode instability threshold will be approached, or possibly even exceeded, in

the region where the mode amplitude is large, and so the mode can become unstable, due to a

combination of energetic and thermal ion kinetic effects.

Our findings suggest that mode existence could be used as a

form of inference for temperature profile consistency in the

radial interval of the mode, thereby extending the tools of

MHD spectroscopy.

In unrelated work we also report on a linear inference

technique we have developed recently infers changes in the

ion slowing down distribution function from changes in

neutron emission during fishbones, and has been applied to

MAST data.

[1] M J Hole et al, First evidence of Alfvén wave activity in

KSTAR plasmas, Plasma Phys. Control. Fusion 55 (2013)

045004


74

P-25: particle in cell simulation of toroidal alfven eigenmodes in

kstar

C. M. Ryu1, H. Rizvi

1, and Z. Lin

2

1POSTECH, Pohang, Korea

2University of California, Irvine , CA 92697, USA


During the 2012-2013 KSTAR campaigns, plasmas with currents up to Ip=600 kA and magnetic fields

B=2-3T were made by using two neutral beams with energies of 80KeV and 90KeV, which induced fast

particles with velocities around 2.7x106 m/s, and the Alfven velocity about VA = 1.5x10

7 m/s. In these

shots, discrete stair-like modes are detected in Mirnov coil (MC)s at frequencies in the range of 100-175

KHz. These modes are shown to much resemble the core localized TAEs observed in JET plasmas [1].

To characterize these modes, we have investigated the TAE excitation in KSTAR by using the

gyrokinetic toroidal code (GTC) [2] with a numerical equilibrium generated by using EFIT for these

shots. The critical plasma shear for these shots is sc=m2/(4n

2q

2ε)~0.74. Because the plasma shear is less

than the critical shear ( s<sc ) in a rather wide range of r/a < 0.75 in KSTAR, discrete Alfven eigenmodes

are expected to occur up to 3/4 radius of KSTAR plasmas [3]. Our GTC simulation shows that multiple

m modes for fixed n are excited at about r/a=0.42 and 0.56 with frequencies 165-145 kHz, which are

consistent with the experimental observation in KSTAR. Detailed analyses of GTC simulation results are

presented.

[1] N. P. Young, et. al. Plasma Phys. Control. Fusion 48 (2006) 295–313.

[2] Z. Lin, T. S. Hahm, W. W. Lee, W. M. Tang, and R. B. White, Science 281(1998) 1835-1837.

[3] J. Candy, B. N. Breizman, J. Van Dam, and T. Ozeki Phys. Lett. A 215(B1996) 299.

75

P-26: flow enabled instabilities in energetic geodesic acoustic

modes (egams)

Zhisong Qu1, Matthew Hole

1, Michael Fitzgerald

2 and Brett Layden

1

1Research School of Physics and Engineering, the Australian National University, Canberra ACT 2601, Australia

2EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon, OX14 3DB, UK


Energetic geodesic acoustic modes (EGAMs)1,2

are axisymmetric energetic particle modes found in

toroidally confined plasmas resulting from the geodesic curvature of magnetic field lines. They are

experimentally observed at half of the conventional GAM frequency and are localized at the core, where

there is a significant fast particle population. Until recently, it was widely believed that EGAMs are

driven unstable by a positive gradient of the fast particles in the velocity space (∂F/ ∂E > 0). However,

unlike previous studies* which treat fast ions kinetically, we consider the thermal ions and fast ions as

different type of fluids with a super thermal flow speed for the latter. Surprisingly, the frequency and

growth rate predicted by our fluid mode agree well with the kinetic theory within the region of validity of

the fluid model, despite the absence of inverse Landau damping in the fluid model. This indicates that

under some conditions, the EGAMs are not driven by wave-particle interaction, but are enabled by flow

effects.

As in previous studies, multiple branches of GAM solutions are found. The dependency of their

frequencies on the q value, the beam transit frequency and the fast particle populations is examined. The

application of our model in the early beam turn on of EGAMs in DIII-D is also discussed.

1 Nazikian, R. et al. Phys. Rev. Lett. 101, 185001 (2008).

2 Fu, G. Phys. Rev. Lett. 101, 185002 (2008).

3 Girardo, J.-B. et al. Phys. Plasmas 21, 092507 (2014).

76

P-27: off-axis nbi-driven energetic particle modes at asdex

upgrade

Ph. Lauber1, B. Geiger

1, M. Maraschek

1, L. Horvath

2, C. Di Troia

6, G. Papp

1, M. Dunne

1, A. Biancalani

1,

M. Schneller1, X. Wang

1, I. Classen

4, V. Igochine

1, A. Mlynek

1, M. García-Muñoz

1;

1,5,V. Nikolaeva

1,3,

L. Guimarais3, NLED Enabling Research Team, and the ASDEX Upgrade Team

1Max-Planck-Institut für Plasmaphysik, Garching, Germany

Email Address of Submitting Author: [email protected] 2Institute of Nuclear Techniques, BME, Budapest, Hungary

3Associação EURATOM/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Tecnico,

Universidade Técnica, 1049-001 Lisboa, Portugal 4FOM Institute Differ - Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM,

3430 BE Nieuwegein, The Netherlands 5Department of Physics, University of Seville, Seville, Spain

6ENEA, Frascati, Italy

The off-axis injection of neutral beam ions (2.5 MW) during the current ramp-up phase in ASDEX Upgrade gives

rise to strongly non-linear energetic particle bursts emerging from the TAE gap. The modes seem to be similar to

observations on JT-60U [Shinohara, 2002-2004] or on spherical tokamaks with the important difference that at

ASDEX Upgrade the ratio of the velocity of injected beam ions compared to the Alfven velocity is far below

1(vNBI / vA) ~ 0.4). The fast ion b in these discharges is transiently comparable or even larger than the thermal b

allowing one to explore a unique parameter space relevant for the stability of burning plasmas. Additionally, a clear

correlation of these bursts and energetic particle driven geodesic acoustic modes (EGAMs) is observed, indicating a

velocity space coupling of both modes.

Based on various diagnostics measurements and beam deposition calculations for the energetic particle distribution

function, a kinetic stability analysis will be shown, investigating the drive mechanism of the EGAMs and the TAE

bursts. The non-linear features of the modes will be discussed.

More generally, these results will allow us to understand in a detailed way the transition from weakly-driven Alfvén

modes to strongly-driven energetic particle modes and the interaction mechanisms of AEs with zonal modes, both

experimentally and theoretically/numerically.

Figure 1: Spectrogram of the magnetic pick-up coil signal in the presence of off-axis (co-direction) NBI drive

(#31213).


from the Euratom research and training programme 2014-2018 under grant agreement No 633053.

The views and opinions expressed herein do not necessarily reflect those of the European Commission.

77

P-28: resistive interchange mode destabilized by helically

trapped energetic ions in lhd plasma

X.D. Du

1, K. Toi

2, S. Ohdachi

1,2, M. Osakabe

1,2, T. Ido

2, K. Tanaka

2, M. Yokoyama

1,2,

M.Yoshinuma1,2

, K. Ogawa2, K.Y. Watanabe

2, M. Isobe

1,2, K. Nagaoka

1,2, T. Ozaki

2,

S. Sakakibara1,2

, R. Seki2, A. Shimizu

2, Y. Suzuki

1,2, H. Tsuchiya

2 and LHD Experiment Group

1The Graduate University for Advanced Study, Toki 509-5292, Japan

2National Institute for Fusion Science, Toki 509-5292, Japan

The resistive interchange mode (RIC) destabilized through resonant interaction with a characteristic

motion of helically trapped energetic ions are observed in Large Helical Device (LHD), called the EIC,

exhibiting bursting character and rapid frequency chirping down [1]. The initial frequency of the EIC is

consistently explained by the mode-particle resonance condition in a non-axisymmetric LHD plasma.

This resonant interaction is clearly found in the rapid changes in the energy spectra of charge exchanged

neutral flux perpendicular to magnetic field line below the injected beam energy of 34keV . The mode

structure has a quite similar eigenfunction of the radial displacement of the RIC. That is, the EIC is well

localized at the mode rational surface, even if the EIC has low poloidal and toroidal mode numbers

m = 1/n = 1, and the eigenfunction is an odd function indicating an island-type shape. The threshold of

helically trapped energetic ions pressure is investigated, i.e., the volume averaged βh⊥ ~ 0.3% and that of

local beta of ~ 0.2% at ι = 1 surface. The EIC also strongly impacts the confinement of helically trapped

energetic ions and induces noticeable losses. The non-ambipolar radial transport of the helically trapped

energetic ions is inferred from the large and sudden drop of plasma potential measured by the heavy ion

beam probe and also from the sudden increase of charge exchanged neutral flux. In addition, the clear

suppression of micro-turbulence measured by a CO2 laser phase contrast imaging is observed with each

EIC burst.

[1] X.D. Du, K. Toi, M. Osakabe et al., Phys Rev. Lett. 114, 155003 (2015)

78

P-29: electron fishbone dynamics studies in tokamaks with the

xhmgc code

V. Fusco, G. Vlad, S. Briguglio, G. Fogaccia

ENEA for EUROfusion, Via E. Fermi 45, 00044 Frascati, Italy

Email Address of submitting Author : [email protected]

The electron fishbone modes are internal kink instabilities induced by suprathermal electrons. Ion

fishbones were first observed experimentally (PDX) [1], opening the path to full theoretical

understanding of these phenomena [2]. Stimulated by experimental evidence of electron fishbones

(DIII-D, Compass-D, FTU, ToreSupra), theoretical analysis has also been extended to the case of modes

excited by fast electrons [3].

It is well known that additional heating of a plasma produces suprathermal particles which, under certain

conditions, could destabilize symmetry breaking modes. Moreover, the dynamics of suprathermal

electrons in present days experiments has analogies to that of alpha particles in future burning plasma

devices; and resonant excitation by fast electron precession resonance may provide a good test bed for

understanding the similar mechanism induced by fusion alphas. For these reasons, it is important to get

insights into the underlying physics processes involved in these phenomena.

In this work, numerical simulations with the HMGC code are systematically carried out in tokamak

equilibria. On the one side, theoretical and experimental results are confirmed, while, on the other side,

numerical simulations give a deeper insight into the e-fishbones dynamics. Linear and non-linear studies

of e-fishbone instability have been performed for standard (peaked on-axis) [4] and inverted (peaked off-

axis) suprathermal electron density profile, with moderately hollow q-profile. It is worth noting that the

two situations are significantly different in terms of the characteristic resonance frequency as well as the

fraction of suprathermal particles involved in the destabilization of the mode, confirming theoretical

expectations. The study of e-fishbone nonlinear saturation mechanisms uses the test particle Hamiltonian

method (TPHM) package [5], illuminating the complicate and unexplored dynamics of these modes.

[1] K. Mcguire et al 1983 Phys. Rev. Lett. 50 891

[2] L. Chen,R.B. White and M.N. Rosenbluth, Phys. Rev. Lett. 52 1122 (1984).

[3] F. Zonca et al. Nuclear Fusion, 47 (2007) 1588–1597.

[4] G. Vlad et al. Nuclear Fusion, 53:083008, 2013.

[5] S. Briguglio et al. Physics of Plasmas, 21:112301, 2014.




79

P-30: linear benchmarks between hymagyc and hmgc codes

G. Fogaccia, G. Vlad, S. Briguglio

ENEA for EUROfusion, Via E. Fermi 45, 00044 Frascati, Italy


The HYMAGYC code [1] is a HYbrid MAgnetohydrodynamics GYrokinetic Code suitable to study

energetic particle (EP) driven Alfvénic modes in general high-pressure axisymmetric equilibria, with

perturbed electromagnetic fields fully accounted for. HYMAGYC is composed by a MHD module

interfaced with a particle-in-cell gyrokinetic (GK) solver. The MHD module solves resistive MHD linear

equations taking into account the EP kinetic response through the divergence of the pressure tensor. The

gyrokinetic module evolves particle flux coordinates in terms of gyrocenter equations of motion and

yields the EP pressure tensor back to the MHD solver. The gyrokinetic ordering k⊥ρH≈1 is assumed.

A linear benchmark activity between HYMAGYC and HMGC [2] code is underway.

The gyrocenter equations implemented in HYMAGYC have been reduced to the guiding-center

description assumed in HMGC, and simulation parameters have been chosen to be consistent with the

HMGC model validity limits; i.e., ρH/a<<1, A⊥=0, a/R0 <<1 and circular magnetic flux surfaces.

First, the GK solvers of HMGC and HYMAGYC have been tested with assigned perturbed

electromagnetic fields, while the MHD modules of two codes have been checked assuming an "ad-hoc"

driving term, treated explicitly. Then, benchmark between HYMAGYC and HMGC codes has been

performed for two test cases, namely: (a) a/R0=0.1, circular shifted magnetic-surface equilibrium with

parabolic safety factor radial profile (q0=1.1, qa=1.9) in presence of a isotropic Maxwellian initial

energetic ion population, toroidal mode number n=2; (b) a/R0=0.1, circular shifted magnetic-surface

equilibrium with parabolic safety factor radial profile (q0=1.71, qa=1.87), n=6 (the so-called ITPA

Energetic Particle Group test case). Comparison of growth-rates of the most unstable modes vs. EP

density, Larmor radius and thermal velocity between HYMAGYC and HMGC will be presented.

[1] G. Vlad et al., 11th IAEA Technical Meeting on Energetic Particles in Magnetic Confinement Systems (Kyiv

2009), paper P–25.

[2] S. Briguglio, G. Vlad, F. Zonca, C. Kar, Hybrid magnetohydrodynamic gyrokinetic simulation of toroidal

Alfvén modes Phys. Plasmas 2 (1995) pp. 3711-3723




80

P-31: kinetic modelling of runaway electron dynamics

A. Stahl1, O. Embréus

1, E. Hirvijoki

1, G. Papp

2, M. Landreman

3, I. Pusztai

1 and T. Fülöp

1

1Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden

2Max Planck Institute for Plasma Physics, Garching, Germany

3University of Maryland, College Park, MD, USA


Abstract In the quest for avoidance or mitigation of the harmful effects of runaway electron formation

[1], a greater understanding of the runaway electron phenomenon is required. Improved knowledge of

runaway electron formation mechanisms, their dynamics and characteristics, as well as transport or loss

processes that may contribute to runaway electron suppression, will benefit the fusion community and

contribute to a safe and reliable operation of reactor-scale tokamaks.

Kinetic simulation is the most accurate and useful method for investigating runaway electron dynamics,

and we recently developed a new tool (called COllisional Distribution of Electrons (CODE) [2]) for fast

and accurate study of these processes. Here, we discuss improvements to the model, which enable us to

study the effect on the runaway electron distribution of important processes such as hot-tail runaway

formation and synchrotron and Bremsstrahlung radiation emission. We also discuss an improved model

for the knockon collisions leading to avalanche runaway electron generation.

The above mentioned processes have important implications for the understanding of many phenomena,

such as the effective critical electric field for runaway electron generation [3], and can even lead to the

formation of non-monotonic features in the runaway electron tail [4]. Such features could drive kinetic

instabilities, suppressing runaway growth. We will discuss the effects of hot-tail generation in connection

with the improved avalanche source, which has the potential to alter the dynamics in the early stages of

the runaway electron evolution.

[ 1 ] E. M. Hollmann, et al., Phys. Plasmas 22, 021802 (2015).

[ 2 ] M. Landreman, A. Stahl and T. Fülöp, Comp. Phys. Comm. 185, 847 (2014).

[ 3 ] A. Stahl, E. Hirvijoki, J. Decker, O. Embréus and T. Fülöp, Phys. Rev. Lett. 114, 115002 (2015).

[ 4 ] E. Hirvijoki, I. Pusztai, J. Decker, O. Embréus, A. Stahl and T. Fülöp, Radiation reaction induced non-

monotonic features in runaway electron distributions, to appear in J. Plasma Phys.

81

P-32: fast-ion d-alpha spectrum during east neutral- beam heated

plasmas

J. Huang1, W.W. Heidbrink

2, M.G. von Hellermann

3, Y. Zhu

2, J. Chang

1, C. Wu

1, Y. Hou

4, W. Gao

1,

Y.Yu4 and EAST Team

1

1Institute of Plasma Physics, Chinese Academy of Sciences, 230031, Hefei, Anhui, China

2University of California, Irvine, California 92697, USA

3FOM Institute DIFFER, Nieuwegein 3430 BE, The Netherlands

4School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui,

230026,China


Based on the charge exchange recombination between fast ions and a neutral beam, fast ion features can

be inferred from the Doppler shifted spectrum of Balmer-alpha light from energetic hydrogenic atoms.

With the upgrade of the Experimental Advanced Superconducting Tokamak (EAST) in 2015, both co-

current and counter-current neutral beam injectors have been available, and each can deliver 2-4 MW

beam power with 50-80 keV beam energy. Based on the available probe beam, the fast ion D-alpha

(FIDA) diagnostic system has been built [1] on EAST to investigate fast ion behavior. The system

includes both tangential and vertical views to study the trapped and passing fast-ion velocity distribution

and spatial profile. Beam modulation method is used here for background subtraction to get net FIDA

signal. For the vertical view, the paired passive view is also available, allowing direct background

subtraction. Since the FIDA diagnostic system was tested in the 2014 campaign, it has been updated to

improve the reliability of the measurements, according to the mechanical problems. In the 2015 summer

campaign, the validation of FIDA diagnostics is carried out under MHD-free neutral-beam heated

plasmas, and the results for fast-ion D-alpha spectrum are compared with the simulated signals.

References [1] J. Huang, et al., Rev. Sci. Instrum. 85, 11E407 (2014).

This work was supported by National Magnetic Confinement Fusion Science Program of China under Contract No.

2011GB101004 and 2015GB110005.

82

P-33: evaluation of fluxes of lost alphas for gamma-ray

diagnostics in iter

V. Goloborodko1,2

, V. Kiptily3, K. Schoepf

1, V. Yavorskij

1,2

1Institute for Theoretical Physics, University of Innsbruck, Austria

2Institute for Nuclear Research, Ukrainian Academy of Sciences, Kyiv, Ukraine

3CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, UK

Email Address of Submitting Author:[email protected]

One of the possible diagnostics of energetic fusion alpha particle loss is gamma-ray diagnostics based on

the measurements of gamma emission produced in nuclear reactions between escaped alphas and a

beryllium target located near the ITER mid-plane [1]. The efficiency of such a diagnostic depends on the

flux of alpha particles with energy E>1.7 MeV (threshold of the nuclear reaction with beryllium) at the

target position. In ITER, due to the high plasma current, losses induced by collisional radial transport

will exceed first orbit losses [2] and hence form a prominent contribution to the charged fusion product

loss. Thus, in the case of low MHD activity, diffusive-convective collisional transport will be mainly

responsible in ITER for the maximum heat loads and fluences caused by fusion alphas.

The paper represents results of modelling of collisional fluxes of alphas escaping from ITER plasmas as

well as their surface and velocity distributions on the plasma facing elements. The simulation is based

on the new full gyro-orbit Monte-Carlo code DOLFI accounting for the effect of TF ripples and RMPs.

A strong modulation of fusion alpha particle loss distributions over toroidal and poloidal coordinates is

demonstrated. Calculations of alpha particle fluxes to the position of the beryllium target supposed for

gamma-ray diagnostics in basic ITER scenarios will be presented.

[1] V. Kiptily, On development of alpha-particle diagnostics in JET, 4th Workshop FIMAD, 19-21 Feb. 2014.

[2] V. Yavorskij, et al., JOFE (2015). DOI 10.1007/s10894-015-9862-2


83

P-34: interpretive and predictive modelling of fluxes of charged

fusion products lost from tokamak plasmas

V. Yavorskij1,2

, Yu. Baranov3, V. Goloborod’ko

1,2, D. Darrow

4, V.G. Kiptily

3, K. Schoepf

1,

C. Perez von Thun3

1Institute for Theoretical Physics, University of Innsbruck, Austria (fusion@oeaw) 2Institute for Nuclear Research, Ukrainian Academy of Sciences, Kyiv, Ukraine

3CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, UK

4Princeton Plasma Physics Laboratory, New Jersey, Princeton, USA


In this study we assess the fluxes of charged fusion products (CFPs) lost from tokamak plasmas as a

result of the radial transport associated with Coulomb collisions. In present day tokamaks with moderate

or low plasma currents these fluxes result in heat loads and fluences onto the surface of plasma facing

components, which can be comparable to or do even exceed those owing to the first orbit loss of CFPs

[1-4]. In ITER-like tokamaks with high plasma currents and low MHD activity the collisional radial

transport is expected to be accountable for the main contribution to CFP losses [5] and correspondingly

responsible for the maximum heat loads and fluences caused by fusion alphas. The paper represents

results of modelling of collisional fluxes of CFPs both from TFTR and JET plasmas with low and

moderate plasma currents as well as of collisional fluxes of alphas escaping from ITER plasmas.

Our simulation is based on the new full gyro-orbit Monte-Carlo code DOLFI accounting for the effect of

TF ripples and RMPs. DOLFI delivers detailed distributions of diffusively-convectively lost fast ions

over the coordinates of the plasma facing surface and over the velocity coordinates as well.

A strong variation of CFP loss distributions over the toroidal and poloidal coordinates is demonstrated.

The modelling results are in satisfactory agreement with measurements of velocity distributions of the

loss additional to the first orbit loss of CFPs in TFTR (so-called “delayed” loss [1]) and in JET

(“anomalous” loss [4]). Results of predictive modelling of heat loads and fluences of fusion alphas for

basic ITER scenarios will be presented.

[1] S. Zweben, et al., Nucl. Fusion 40 91 (2000).

[2] K. Sugiyama, et al., J. Nucl. Mater., 329–333 874 (2004).

[3] V. Yavorskij, et al., Nucl. Fusion 43 1077 (2003).

[4] Yu. Baranov, et al., EPS 2010, paper P1.141.

[5] V. Yavorskij, et al., JOFE (2015). DOI 10.1007/s10894-015-9862-2


84

P-35: diagnosis of mirror trapped particles and excitation of

energetic particle (ep) driven modes in lvpd

A. K. Sanyasi, L. M. Awasthi, P. K. Srivastava, S. K. Mattoo and P. K. Kaw

Institute for Plasma Research, Gandhinagar-382428, India


The LVPD plasma demonstrates nice exhibition of electron trapping in a belt region. This

comes into existence only when EEF1-3

is made active. The active EEF modifies the applied

magnetic field of LVPD ( 6.2zB G ) by its strong perpendicular field of 150xB G . Energetic

electrons are traced through peak floating potential measurements (mimics presence of energetic

electrons) and approximately (5- 10) % of bulk plasma electrons, which are energetic, are

trapped in the region of plasma turbulence. In this paper, results demonstrating trapping of

energetic electrons measured through various diagnostic techniques will be presented. The

results from these diagnostics assume significance as they presents better representation of

energetic electrons than what obtained through Electron Energy Distribution Function (EEDF),

derived from I/V characteristics of Langmuir probe data. The EEDF does not offer clear

distinction between for the plasma, when trapped electrons are present and absent in the region.

Also, an effort is made to correlate these electrons with the excited plasma turbulence. The

),( k spectrum of the turbulence in the region suggest that long and short wave length modes

exist along and across zB with their respective wave numbers as, ||/ 60 70k k . Comparison

of diagnostics outcome and mode identification of observed, low frequency ( ~ LH ce ) EP

driven turbulence, its correlation with the instabilities excited in magnetosphere and tokamaks

will be presented in the conference.

References

1. S. K. Singh, P. K. Srivastava, L. M. Awasthi, et. al. Rev. Sci. Instrum., 85, 033507 (2014).

2. S. K. Mattoo, S. K. Singh, L. M. Awasthi, et. al. Phys. Rev. Lett. 108, 255007 (2012).

3. A. K. Sanyasi, L. M. Awasthi, S. K. Mattoo, et. al. Phys. Plasmas, 20, 122113 (2013).


85

P-36: diagnosing mev range deuterons with neutron and gamma

ray spectroscopy at jet

M. Nocente1,2

, J. Eriksson3, F. Binda

3, C. Cazzaniga

2,4, S. Conroy

3, G. Ericsson

3, L. Giacomelli

2,

G. Gorini1,2

, C. Hellesen3, A. Hjalmarsson

3, A. S. Jacobsen

5, V. Kiptily

6, M. Mantsinen

7,8, M. Salewski

5,

M. Schneider9, S. Sharapov

6, M. Skiba

3, M. Tardocchi

1,2, M. Weiszflog

3 and JET Contributors

EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, UK 1Dipartimento di Fisica ’G. Occhialini’, Università degli Studi di Milano-Bicocca, Milano, Italy

2Istituto di Fisica del Plasma ’Piero Caldirola’, Associazione EURATOM-ENEA-CNR, Milano, Italy

3Department of Physics and Astronomy, Uppsala University, Sweden

4ISIS Facility, Rutherford Appleton Laboratory, Science Didcot, UK

5 Technical University of Denmark, Department of Physics, DK-2800 Kgs. Lyngby,Denmark

6CCFE, Culham Science Centre, Abingdon, UK

7Catalan Institution for Research and Advanced Studies, Barcelona, Spain;

8Barcelona Supercomputer Center, Barcelona, Spain

9CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France

A particularly effective heating scheme to accelerate ions to the MeV energy range at JET is to couple

ion cyclotron radio frequency (ICRF) heating at the third harmonic into an injected deuteron beam in a

deuterium plasma. This heating mechanism was the basis for a dedicated experiment in the latest JET

campaign [1,2] and is of special interest for diagnostic applications, as it allows testing the capability of

the present systems to diagnose the fast ion energy distribution in preparation of the forthcoming

deuterium-tritium campaign.

In this work we present the experimental observations made in the latest JET third harmonic acceleration

experiment (summer 2014) by means of an extended set of neutron and gamma-ray spectrometers

observing the plasma along a vertical and an oblique line of sight. Data from the whole set of detectors

(which include high resolution gamma-ray spectrometers, a time of flight neutron spectrometer, a

neutron camera as well as a scintillator and diamond neutron detectors, operated simultaneously for the

first time) are used to determine parameters of the fast ion energy distribution. We also discuss the

sensitivity of the different diagnostics in fast ion phase space and relate it to the measurements. A one

dimensional, extended Stix model of the deuteron velocity distribution is used first to extract the energy

cut-off in the deuteron phase space and the ICRF coupling constant from neutron and gamma-ray data. It

is found that, while detectors sharing the same line of sight provide consistent results within error bars,

the parameters derived from measurements along different lines of sight do not appear to agree. In

particular, as also revealed by velocity space weight function calculations of neutron and gamma-ray

spectroscopy, oblique measurements show a certain sensitivity to the spatial distribution and pitch angle

structure of the energetic ions around the ICRF resonance, which is not correctly portrayed by the

adopted one dimensional model. A more detailed framework based on first principle distribution

functions calculated by the PION and SPOT/RFOF codes is finally used to improve our description of

neutron and gamma-ray emission during the experiment and compared to data for both lines of sight.

[1] S. Sharapov et al. "Fast Ion D-D and D-3He Fusion on JET", this meeting: [2] M. Schneider et al. "Modelling 3

rd

harmonic Ion Cyclotron acceleration of D beam for JET Fusion Product Studies experiments", this meeting

86

P-37: a comparison of reconstruction methods for inferring the

fast-ion distribution function from multiple fida measurements

L. Stagner and W.W. Heidbrink University of California, Irvine, California 92697, USA

A.S. Jacobsen and M. Salewski Technical University of Denmark, Department of Physics, DK-2800 Kgs. Lyngby, Denmark

B. Geiger, M. Weiland, and the ASDEX Upgrade team Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany

The Fast-ion Dα (FIDA) diagnostic measures light that energetic particles emit in fusion plasmas.

The diagnostic is sensitive to different velocity space regions depending on the viewing angle relative to

the magnetic field.[2] Consequently, viewing chords that share a radial location give different, yet still

valid, results. Velocity space tomography allows us to combine the rich information contained in FIDA

spectra from these viewing chords to infer the complete local fast-ion distribution function from the

different partial views[1]. Tomography involves solving a system of linear equations which are often ill-

conditioned and consequently sensitive to measurement error. There are a number of ways to regularize

these types of systems to make them amenable to physical solutions. These methods include Truncated

Singular Value Decomposition (TSVD), Zeroth and First Order Tikhonov Regularization, the Maximum

Entropy Method, and Minimum Fisher Information Regularization. The best regularization method is

often application dependent. In this work we present a survey of the different regularization methods

using realistic synthetic data to determine the most effective regularization method for velocity space

tomography. Preliminary results show, for realistic distributions, that Minimum Fisher Information

Regularization produces the best results. We also demonstrate the application of the described methods

to real data to study the redistribution of fast-ions during a sawtooth crash at ASDEX Upgrade. An

extension of velocity space tomography to allow for the inference of the full fast-ion distribution in

constants of motion space will also be presented.

1] M. Salewski, B. Geiger, A. S. Jacobsen, M. García-Muňoz, W. W. Heidbrink, S. B. Korsholm, F. Leipold, J.

Madsen, D. Moseev, S. K. Nielsen, et al. Measurement of a 2d fast-ion velocity distribution function by

tomographic inversion of fast-ion d-alpha spectra. Nuclear Fusion, 54(2):023005, 2014.

[2] M. Salewski, B. Geiger, D. Moseev, W. W. Heidbrink, A. S. Jacobsen, S. B. Korsholm,

F.Leipold, J. Madsen, S. K. Nielsen, J. Rasmussen, et al. On velocity-space sensitivity of fast-ion d-alpha

spectroscopy.

Plasma Physics and controlled Fusion, 56(10):105005, 2014.

87

P-38: preliminary results of the east integrated energetic

neutral particle analyzer and its conceptual design on the

hl-2a/m tokamaks

Y.B. Zhu1, J.Z. Zhang

2, G.Q. Zhong

2, L.M. Yu

3, J. Lu

3, W.W. Heidbrink

1,

B.N. Wan2, J.G. Li

2, Y. Liu

3, X.T. Ding

3, and X.R. Duan

3

1Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA

2Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China

3Southwestern Institute of Physics, Chengdu 610041, China


A package of full function integrated, compact silicon photodiode based solid state neutral particle

analyzers (ssNPA) has been successfully developed, implemented and commissioned for energetic

particle (EP) relevant studies on the Experimental Advanced Superconducting Tokamak (EAST) [1,2].

The system consists of 7+9 individual channels on two long vertical up-ports and 16+16 arrays mounted

on a retractable feedthrough on a horizontal port.

The system functionality has been proved by the preliminary data obtained from the EAST 2014 and

2015 summer campaigns. Significant signal enhancements from both ion cyclotron resonant heating

(ICRH) and neutral beam injection (NBI) are observed, with no clear direct response to either lower

hybrid wave (LHW) or electron cyclotron resonant heating (ECRH) under similar plasma conditions.

ssNPA data is consistent with neutron flux detected by traditional counters and a set of new scintillators.

Significant EP related engineering upgrades and experimental plans have been setup on the HL-2A and

its successor HL-2M tokamak [3], as well as on the EAST. Compared to the complicated EAST

engineering and operational realities, the Chengdu tokamaks provide ssNPA diagnostics with better

accessibility and much simpler in-vacuum environment. Aiming at simultaneous measurements with fast

temporal, fine spatial and coarse energy resolutions, the HL-2A/M ssNPA conceptual design and

engineering optimization details will be presented.

References

[1] Y.B. Zhu et al., Development of an integrated energetic neutral particle measurement system on experimental

advanced full superconducting tokamak, Rev. Sci. Instrum. 85, 11E107 (2014).

[2] Y.B. Zhu et al., Compact solid-state neutral particle analyzer in current mode, Rev. Sci. Instrum. 83, 10D304

(2012).

[3] Q.W. Yang et al., Diagnostics for energetic particle studies on the HL-2A tokamak, Rev. Sci. Instrum. 85,

11D857 (2014).

[4] J. Y. Cao et al., Conceptual design of 5MW-NBI injector for HL-2M tokamak, Fus. Eng. Des. 88,

(6-8) 872-877 (2013).

88

P-39: fast ion d-d and d-3he fusion on jet

S.E.Sharapov, T.Hellsten1, V.G.Kiptily, T.Craciunescu

2, J.Eriksson

3, M.Fitzgerald, J.-B.Girardo

4,

V.Goloborod’ko5,6

, A.Hjalmarsson3, A.S.Jacobsen

7, T.Johnson

1, Y.Kazakov

8, T.Koskela

9,

M.Mantsinen10

, I.Monakhov, F.Nabais11

, M.Nocente12

, C. Perez von Thun5, F.Rimini, M.Salewski

7,

M.Santala9, M.Schneider

4, M.Tardocchi

12, M.Tsalas, V.Yavorskij

5,6, V.Zoita

2 and JET Contributors*.

CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, UK 1KTH Royal Institute of Technology, SE-100 44, Stockholm, Sweden

2National Institute for Laser, Plasma and Radiation Physics, Bucharest, Romania

3Dept. of Physics and Astronomy, Uppsala University, Uppsala, Sweden

4CEA, Cadarache, France

5Institite for Theoretical Physics, University of Innsbruck, Austria

6Institute for Nuclear Research, Ukraininan Academy of Sciences, Kiev, Ukraine

7Technical University of Denmark, Department of Physics,DK-2800 Kgs. Lyngby, Denmark

8LPP-ERM/KMS, TEC Partner, Brussels, Belgium

9Aalto University, PO Box 14100, FIN-00076, Aalto, Finland

10ICREA-Barcelona Supercomputer Center, Barcelona, Spain

11IST, Centro de Fusao Nuclear, Lisbon, Portugal

12CNR-IFP and University di Milano-Bicocca, Milan, Italy

*See Appendix of F. Romanelli et al., Proc. 25th IAEA FEC 2014, Saint Petersburg, Russia

Third harmonic ICRH [1,2] has been shown at JET to be an effective tool for accelerating NBI-produced

beam ions to the MeV energy range, suitable for studying ITER relevant fast particle physics, as well as

for preparing JET fusion product diagnostics for a future D-T campaign. By adding 3 MW of ICRH

power at 3rd harmonic to 3-4 MW of D NBI in D plasma, it was possible in recent experiments to

increase the yield of D-D neutrons by an order of magnitude, up to 7·1015

n/s. Neutron emission spectra

measured in these experiments,

both by time-of-flight analysis and using a novel diamond detector, reveal broad spectra with neutron

energies up to ~6 MeV for D-D neutrons [3]. This broadening of the D-D neutron spectra results from

ICRH acceleration of NBI-produced D with starting energy ~100 keV into the MeV energy range.

Control of the D-D neutron energy spectrum was demonstrated by varying plasma density, ICRH power,

and pitch-angle of NBI, which play a key role for the coupling between the beam and ICRH. The

experiment was extended to ICRH acceleration of D beams in D-3He plasmas with amounts of

3He

increasing discharge-bydischarge up to D:3He ≈ 70:30. The aneutronic D-

3He fusion, giving birth to 15

MeV protons and 3.7 MeV alpha-particles has been studied on JET before [4]. In contrast to 3He

minority ICRH [5] and 3He NBI [6], the ICRH acceleration of D beam in D-3He plasma generates a fast

Distribution function with a cut-off in energy, which is easy to control. The rate of D- 3He fusion was

measured from 17 MeV γ-rays produced by D(3He, γ)

5Li reaction and found to be ~10 kW. High

resolution γ-spectrometry, NPA, scintillator probe, and Faraday cups were all employed for measuring

ICRH-accelerated D ions and charged fusion products of both D-3He and D-D reactions. Analysis of the

experiments with the suite of ICRH-modelling tools PION, SELFO, and SPOT/RFOF is found to agree

with the measured neutron and γ-ray spectra and profiles [7,8]. Remarkably long sawtooth-free periods

of up to ~2.5 s were obtained in these plasmas and Alfven Eigenmodes were excited. These results pave

the way for further experiments such as counteracting the effective, but ultimately undesirable sawtooth

stabilisation by fast ions observed in the experiment using a separate ICRH source, as well as for

investigating fast ion effects on AEs and other plasma instabilities.

This work has received funding from Euratom and the RCUK Energy Programme [grant number EP/I501045].

The views and opinions expressed herein do not necessarily reflect those of the European Commission.

[1] L. G.Eriksson et al., Nucl. Fusion (1998); [2] M.Mantsinen et al., Phys. Rev. Lett. 88, 105002 (2002); [3] M.Nocente, this

Conference; [4] P.E.Stott, Plasma Phys. Control. Fusion 47, 1305 (2005); [5] J.Jacquinot, G.Sadler, Fusion Technology 21, 2254

(1992); [6] F.B.Marcus et al., Plasma Phys. Control. Fusion 34, 1371 (1992); [7] M.Schneider, this Conference ; [8]

M.Mantsinen, this Conference.

89

P-40: measurement of phase space structure of fast ions

interacting with Alfvén eigenmodes

K. Nagaoka1,2,3

, M. Osakabe1,2

, M. Isobe1,2

, K. Ogawa1,2

, Y. Suzuki1,2

, S. Kobayashi3, S. Yamamoto

3, Y. Miyoshi

4,

Y. Katoh5, J.M. Fontdecaba

6

1National Institute for Fusion Science, Toki, 509-5292, Japan

2The Graduate University for Advanced Studies, Hayama, 204-0193, Japan

3 Institute of Advanced Energy, Kyoto University, Uji, 611-0011, Japan

4Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan

5Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan

6 Laboratorio Nacional de Fusión CIEMAT, Madrid, Spain


Experimentally observed Alfven eigenmodes (AEs) show nonlinear behaviors such as intermittency, fast

sweep in frequency and so on. In order to understand such nonlinear behaviors of AEs, it is widely

recognized that the phase space dynamics have to be taken into account. However, there are few direct

measurements of phase space structure in experiments so far. Here, we propose to apply the wave-

particle interaction analyzer (WPIA) technique being developed for magnetosphere plasma physics (ERG

project) to magnetically confinement fusion experiments.

The concept of WPIA is a phase detection between particle flux and the wave for the quantitative

evaluation of energy transfer between them. We have developed a high speed pulse analyzer system for

WPIA using the field programmable gate array (FPGA) module, and installed the system to the large

helical device (LHD) . One channel of Mirnov signal and eight channels of semi-conductor fast neutral

analyzer (Si-FNA) signals are digitized with sampling rate of 50MS/s (maximum), which is significantly

higher (factor of 104) than that of conventional pulse height analyzer technique and enable us to evaluate

the phase with respect to the wave. The particle detection time and particle energy are recorded for all

particles detected by the Si-FNAs. The detail of the system and some phase space structures observed in

LHD experiments will be discussed in the meeting.).

Fig. 1 Conceptual drawing of wave-particle interaction analyzer (WPIA


90

P-41: damage of plasma facing components due to fast-ion

Losses in the asdex upgrade Tokamak

J. Galdon-Quiroga1, M. Garcia-Munoz

1,2, R. Bilato

2, B. Bobkov

2, S. Fietz

2, J. Garcia-Lopez

1,

V. Igochine2, N. Lazanyi

3, M. Mantsinen

4, M. Maraschek

2, T. Odstrčil

2,

M. Rodriguez-Ramos1, L. Sanchis-Sanchez

1, B. Sieglin

2, A. Snicker

5, G. Tardini

2,

D. Vezinet2 and the ASDEX Upgrade Team

1FAMN Department, Faculty of Physics, University of Seville, Seville, Spain

2Max-Planck-Institut fur Plasmaphysik, Garching, Germany


4ICREA-Barcelona Supercomputing Center, Barcelona, Spain


Fast-ion losses have been observed to cause severe damage to plasma facing components (PFC) in

ICRH-heated plasma. The fast-ion losses measured by scintillator based fast-ion loss detectors (FILD)

[1] are in the MeV range with pitch-angles corresponding to large trapped orbits as expected for ICRH

ions. In addition, a kink mode appears shortly after a sawtooth crash during the ICRH heating phase. The

internal structure of the kink mode is reconstructed by means of SXR tomography. A linear dependence

is found between the amplitude of the coherent losses, correlated with the kink mode magnetic

perturbation, and the amplitude of the latter. Moreover, a modulation of the velocity-space of the

coherent losses is observed by FILD. The temporal evolution of the losses is correlated with the heat load

measured by an infra-red camera looking at the FILD head. The fast-ion distribution arising from the

synergy between the ICRH and NBI heating is simulated using the TORIC/TRANSP and PION codes.

The Monte Carlo orbit-following code ASCOT [2] is used to account for the resonant and non-resonant

interaction between the kink mode and the MeV ions. The key experimental observations and modelling

results will be presented.

[1] M. Garcia-Munoz et al., Rev. Sci. Instrum. 80, 053503 (2009).

[2] E. Hirvijoki et al., Comput. Phys. Commun. 185, 1310 (2014).

91

P-42: further acceleration of beam ions by 2nd harmonic ion

cyclotron heating in asdex upgrade

M. Weiland, B. Geiger, R. Bilato, P. A. Schneider, G. Tardini

and the ASDEX Upgrade team1

Max-Planck-Institut für Plasmaphsyik, Garching, Germany

The coupling of radio waves to suprathermal ions is an important physics aspect for future fusion

devices. In ITER, 2nd harmonic ion cyclotron resonance heating of tritium is one of the foreseen ICRF

schemes, along with He-3 minority heating. The 2nd harmonic heating has the benefit, that it can

accelerate the main ion species directly, however it is only possible for ions with large Larmor radii (with

respect to the RF wave length). The resonant wave absorption results in a non-Maxwellian distribution of

fast ions, which heats the bulk plasma by collisions. It is therefore crucial to understand these fast-ion

distributions, to know their transport behaviour and ensure their confinement.

The tokamak ASDEX Upgrade has a large set of fast ion diagnostics and is therefore very well equipped

for fast-ion studies. The 2nd harmonic heating can be studied with 5 MW of ICRF, which is normally

used for H minority heating, and hence is resonant with D ions at the 2nd harmonic. The D beam ions

(i.e. from 60 keV NBI) have large enough Larmor radii for effective 2nd harmonic absorption.

The fast-ion radial density profile can be measured with the fast-ion D-alpha (FIDA) diagnostic. It has

been upgraded recently to five FIDA views, which allows to reconstruct the distribution in 2D velocity

space. With neutral particle analyzers, the H and D energy spectra can be measured separately. Neutron

measurements are very sensitive to fast D ions because of resulting D-D fusion reactions and hence are a

valuable tool for estimating the high energetic D ion distribution.

While the effect of 2nd harmonic heating can be observed directly in each of these diagnostics, we have

carried out a quantitative comparison between these diagnostics and towards theoretical predictions by

TORIC/SSFPQL and TORIC/TRANSP. The results of these studies will be presented.

Documents

Analysis of ITER Materials and Technologies · 2016. 12. 8. · Energetic particles and collective phenomena 2 Chair: H. Berk 13.30-14.10 I-7: A. Biancalani Non-perturbative nonlinear