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1
Experimental Summary
• Scenarios• Diagnostics• Runaways• Instabilities• Fast-ion Transport
2
Disclaimer
If I lost your summary slide, I’m sorry!
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Outline
• Scenarios• Diagnostics• Runaways• Instabilities• Fast-ion Transport
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Deuterium beams are now injected in LHD
• A comprehensive set of neutron instruments enable improved diagnosis of confined fast ions
O-14 Isobe
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P-21Deuterium beams are employed in an investigation of collisional processes
P-21 Nuga
• Used to validate a Fokker-Planck code
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Neutral-beam injection experiments are now conducted on TCV
• NPA & FIDA data suggest confinement below classical
O/P-17 Testa
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An “afterglow” regime with alpha-driven TAEs seems accessible in JET
O-3 Dumont
• Look for alpha-driven TAEs after beams shut off as in TFTR
• Can produce high neutron rates w/o ICRF• TRANSP prediction based on obtained
discharge is promising
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Observation of MeV range ions in ICRH experiments with the three ions scenarios at JET
Page 8
- A novel ICRH scheme that exploits the favourable polarization properties of the electric field at the L cutoff layer in 3 species plasmas has been developed
- MeV range fast ions were generated and observed by a number of diagnostics, especially gamma-ray and neutron spectroscopy. Fast ion driven MHD leads to redistribution and losses of the most energetic ions (2-3 MeV)
interesting new scheme for fast ion physics studies!
- The scheme can be applied to generate MeV range 4He ions as a way to anticipate α particle physics and prepare DT experiments at JET and ITER
Increased gamma-ray emission (larger fast ion content) with the 3 ion scheme (red) compared to minority heating (blue) for the same
RF power
Tailoring of the fast ion profile by changes of the antenna phasing from dipole (left) to π/2 (right) as demonstrated by poloidal images
of gamma-ray emission from the plasma
M. Nocente, Y. Kazakov et al.
I-6 Nocente
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Outline
• Scenarios• Diagnostics• Runaways• Instabilities• Fast-ion Transport
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An imaging neutral particle analyzer is being installed on DIII-D
pinhole
stripping foils
collimation box• The neutrals are stripped by a
carbon foil• The “detector” is a scintillator-based
magnetic spectrometer as in a Fast-ion Loss Detector
P-4 Xiaodi Du
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On NSTX-U, FIDA signals from edge neutrals are as large as signals from injected neutrals
• Red is “active” signal• Blue is “passive” signal
P-9 Guangzhou Hao
• Edge neutrals also important in edge FIDA measurements in ASDEX-U (Jacobsen)
12
A gamma-ray diagnostic for lost alphas is proposed for ITER
• A reference view is needed for background• Estimated signal-to-noise: 1/3
O-15 & I-3 Kiptily
Fast deuterons & α-particles from nuclear reactions identified and the anomalous neutron rate in H-plasmas were explained
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Classical Distribution Reconstruction
F(E,Rm)
F(Rm,p)
F(E,p)
F(E,Rm)
F(Rm,p)
F(E,p)
Orbit-based weight functions enable improved inference of distribution function
O-11 Stagner
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New analysis of reflectometer data yields larger amplitudes for CAE & GAE eigenfunctions
GAEs
CAEs
I-7 Crocker
• Still doesn’t explain observed electron transport• Many similarities but some differences from
calculated modes
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Outline
• Scenarios• Diagnostics• Runaways• Instabilities• Fast-ion Transport
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QM/kinetic modeling explains stronginfluence of partially ionized impurities on runaway beams
• Massive gas injection dissipates beam
I-5 Papp
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Synchrotron emission used to infer runaway distribution function
O-8 Hoppe
• Weight function for synchrotron image depends on forward cone, synchrotron rate (B), line integral, and camera sensitivity
18 A. Lvovskiy/IAEA-TM-EP/9-2017
Synchrotron radiation limits hardness of gamma spectrumT1
T1
T2
T2
T3
T3
BT increase affects high-energy RE the most
O-9 Lvovskiy
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A new code models the runaway distribution function
P-32 Spong
• Whistler waves driven by runaways were observed for the first time
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Runaways drive whistler & plasma waves in different parts of phase space
P-43 Chang Liu
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Outline
• Scenarios• Diagnostics• Runaways• Instabilities• Fast-ion Transport
Measured frequencies fci at LFS and HFS are different and correspond to local ICR frequency fci ∝ Bt, fci ∝ 1/mi, fci ≠ f(n) Up to 9 harmonics could be resolved
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2
5
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7
3
4
ICE in Ohmic hydrogen and deuterium plasmasin TUMAN-3M in the absence of energetic particles
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f1 = 8,7 MHz
2
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5 6 7 8 9
Ion Cyclotron drift instability (ICDI) in inhomogeneous plasma was predicted by Mikhailovsky & Timofeev, J.Exp.Th.Phys. 44 (1963) 919, and Mikhailovsky, NF 11 (1971) 323,
ICDI develops at vicinity of fci and its harmonics Inhomogeneity criterion for ICDI:
⁄𝜌𝜌𝑖𝑖 𝐿𝐿 ≥ 2 ⁄𝑚𝑚𝑒𝑒 𝑚𝑚𝑖𝑖⁄1 2, 𝐿𝐿 = 1
𝑛𝑛𝑑𝑑𝑛𝑛𝑑𝑑𝑑𝑑
−1
𝜌𝜌𝑖𝑖 ≈ 0.07 cm, → 𝐿𝐿 < 2 cm - reasonable for TUMAN-3M edge ICE in NBI shots are also detected, but frequency corresponds to central ICR
P-2 Askinazi
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Central & Edge ICE observed in DIII-D
I-10 Thome
• ICE frequency spectra depends on beam geometry
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CAEs in DIII-D are sensitive to beam geometry
O-13 Tang
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TAE frequency tracks change in Alfven velocity during pellet injection
I-8 Sharapov
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JET Antenna measurements of TAE damping are consistent with calculated radiative damping
P-19 Nabais
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Chirping is common in negative triangularityplasma as theoretically predicted
O-2 Van Zeeland
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Modes change their radial structure as they chirp in frequency in TJ-II
P-17 Melnikov
Nonlinear interaction between EGAMs and TAEs is observed
P. Zs. Poloskei et al. IAEA-TCM-EP 2017 P-26
• Signal processing method was developedto investigate the possible nonlinearcoupling between different transient(chirping) plasma waves
• Dedicated experiments were carried outon ASDEX Upgrade
• Nonlinear interaction has an amplitudethreshold
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Off-axis beams drive fewer Alfvén eigenmodes
P-13 Kramer
5.6 5.7 5.8 5.9 6.00
50
100
150
200
Freq
uenc
y [k
Hz]
Time [sec]
-500
0
500
0
1
n e_
bar [
1019
m-3
]
0
1
2
3
4
5
Te0
[keV
]
0.0
0.5
1.0
1.5
2.0
Neu
tron
rate
[1013
n/s
]
ECH138729
5.6 5.7 5.8 5.9 6.00
50
100
150
200
Time [sec]Fr
eque
ncy
[kH
z]
-500
0
500
0.0
0.5
1.0
1.5
n e_
bar [
1019
m-3
]
0
1
2
3
4
5
Te0
[keV
]
ECH138730
0.0
0.5
1.0
1.5
2.0
Neu
tron
rate
[1013
n/s
]
138730
ECH reduces Alfvén eigenmodes in LHDP-22K. Nagaoka, et al.,
The fast ion profile can be controlled by combination of IS operations and plasma positions
Highlights(case 2)Center-focused NBI deposition Broad NBI deposition
• The comparison of two plasmas with the same neutron rate indicates that AE activities were stronger with center-focus NBI deposition
• Significant reduction of AE activities with ECH were observed in LHD
How to control fast ion profile
Active Control of Alfven Eigenmodesin the AUG Tokamak
• Localized ECRH and ECCD have strong impact on AE activity
• modifications of thermal plasma profiles seem to be key
• Externally applied 3D fields can be used to manipulate the fast-ion distribution in phase-space
• Suppression / excitation of NBI driven TAEs achieved on command by varying poloidal spectrum of externally applied 3D Fields I-2 Garcia-Munoz
RJ Buttery/FES Summer Visit 2018/33
• Beam current variation at fixed voltage identifies energetic particle mode (CAE) threshold
– mode disappears as beam current decreases
– controls beam ion density directly
• Neutral beam efficiency is improved in high qmin steady state plasmas when coherent instabilities are reduced through beam IV tailoring
In-shot Control of Neutral Beam Current/Voltage Reduces Fluctuations and Improves Beam Ion Confinement
Key Enhancements: Variable Perveance Neutral Beams
P-44 Pace
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Resistive interchange modes cause large losses but can be stabilized by ECH
O-16 Ohdachi
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Fast ions alter the stability of Neoclassical Tearing Modes
O-22 Heidbrink
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Outline
• Scenarios• Diagnostics• Runaways• Instabilities• Fast-ion Transport
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Fast-ion losses from 3D fields depend sensitively on the poloidal spectrum
O-6 Junghee Kim
• Spectrum altered through coil “misalignment” in KSTAR
• Similar effects on AUG & DIII-D
38
In spherical tokamaks, sawtooth transport is similar to conventional tokamaks
P-16 Deyong Liu
• Passing particles more affected than trapped particles
• Kadomtsev model overestimates transport
Beam ion acceleration during ELMs is observed in the ASDEX Upgrade tokamak
• Velocity space structuressuggest a resonantinteraction between fast-ionsand the E|| arising in the ELM crash
Measured fast ion distributionis reconstructed usingtomographic technique
• Toy model reproduces keyaspects of the accelerationmechanism:
Energy gain
Resonances
J. Galdon-Quiroga | 15th IAEA TM EP | Princeton | 5th-8th September 2017 39O-23 Galdon
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Neoclassical Tearing Modes can cause appreciable transport in ASDEX-Upgrade
• Large (2,1) mode causes reduction in FIDA profile• Modest (3,2) has no detectable effect
I-12 Jacobsen
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Resistive Interchange Mode causes large losses w/ deuterium injection
Relationship of drop rates of total neutron emission rate and magnetic fluctuation induced by EICs.
P-34 Bando
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Measured FIDA profile during strong Alfvénactivity is consistent with predicted profile
• Eigenfunctions matched to measurements
• Orbit following yields “kick” probabilities
O-1 Daniel Lin
43
JET scintillator detector measures new loss phenomena
• Non-resonant losses of fusion products by fishbones
• Fast-ion losses related to EAEs
I-3 Kiptily
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