Facility Status - Massachusetts Institute of Technology · *Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, P.R. China The Engineering Design of ARC: A Compact,

Facility Status05/20/2015

Outline

• Machine Status• Alternator• Engineering Systems• Diagnostic Systems• In-vessel work• Short Term Schedule• SOFE

Machine Status

• Alternator to full speed on 04/08/15• Pump-down on 04/17/15• C-Mod began plasma operations on 04/30/15 after one day of

power system testing• Discharge on first plasma attempt• Full length discharges by the end of the day

• Currently nearing the end of the plasma conditioning phase of operation• Clean plasma facing surfaces• Reduce hydrogen levels• Boronization next week will mark entry into research ops

MIT Alternator Repair and Inspection

• Rotor passed all electrical tests• Stator passed all electrical tests • Flywheel passed UT tests• Bearings refurbished• All 1st and 2nd turns of the #1 and #2 coils of all poles

were inspected• Instrumentation has been reinstalled and calibrated• Checks of all protection systems completed including

Is-limiters (explosive fuses)• Rotor balance checks completed• Rotor on turning gear by 03/16/15• Insurance covers all repair costs

Engineering Systems

• ICRF• Four new enhanced anode FPA tubes on order (1st

tube to ship 04/30/2015, 2nd 05/30/2015)• Waiting for CPI to update us on delivery dates• Manufacturing of anodes has delayed shipment

• New grid regulators (from PPPL) have been installed and are operational.

• All transmitters successfully brought back into operation for FY2015 campaign

• Antennas undergoing conditioning: 2.75 MW from D&E and 1.5 MW from J thus far

• D and E are limited by weak damping (H/D)• FA J antenna had control issue resulting in false

positives – 22 kV in vacuum

Reactive Bonding

Grid Regulators

Engineering Systems

• LH Operation• Launcher was refurbished during up-to-air and calibrations

were checked• 800 kW coupled to plasma thus far

Reactive Bonding

Diagnostic Systems

Update on RFQ accelerator refurbishment in support of AIMS

David TerryEd Johnson

Zach HartwigBrandon SorbomLeigh Ann Kesler

Bill BeckPete Stahle

Rick Murray

Slides Prepared by Zach Hartwig and Dave Terry

Refurbishment of RFQ ion source is nearing completion; first full system tests expected mid-June

Review: The RFQ accelerator is the core of the AIMS diagnostic

Difficulties achieving full energy, full current beam led to full inspection; revealed need for substantial internal maintenance, alignment (end-2014)

Careful, methodical work by C-Mod team for complete refurbishment is now underway; we hope for full system tests by mid-June 2015

Complete disassembly, documentation, drawings completedRF cavity completely cleaned, restored, and modeled in RF softwareIon source and optics characterization, alignment, optimizationFull 3D laser-based alignment of all components Consulting closely with world-experts in RFQ design

AccSys (original manufacturer of this RFQ)Bob Hamm (original designer of this RFQ)

Cross section drawings of the RFQ accelerator

RFQ RF Cavity (work completed early 2015)

Ion source and lens(work to-be complete by mid-June)

Components of accelerator need to be very precisely aligned (a few mils)

The RFQ RF cavity has been completely cleaned and restored as close to original state as possible

After cleaning

All RF characterization matchesoriginal specification; cavity nowbright shiny conducting copper

Before cleaning

The RFQ beam imager installed in the RFQ source

Faraday Cup BNC Out

Pearson Current Monitor BNC Out

Phosphor Screen/Faraday CupBNC Out

• Phosphor screen can be moved along axis

• Digital camera measures position of beam

• CMM measures position of flange faces

Fitting program developed for rapid 2D Gaussian fit of beam spot; enables precision beam location in space

Complete refurbishment of RFQ ion source is nearing completion; first full system tests expected mid-June

Near-terms steps:All necessary beam images acquired (mid-May)Full 3D beam reconstruction, analysis complete (end-May)Complete precision alignment of complete system and reassembly

in the experimental hall (early-mid June)Full beam tests (mid-to-late June)

Provided the above goes as planned, the RFQ would be reinstalled on C-Mod in July and AIMS would commence operation soon afterwards

MSE Upgrade

• Greatly improved background subtraction• Improved detectors and filters• System installed and ready for operation as DNB comes back online• Upgrade to MSE analysis software to handle new hardware and much

more data is ongoing

Polychromators Polychromators Rack Mounted

O-mode Reflectometer Power Supply Upgrade

• New consolidated power supply designed by PPPL was delivered and successfully powered up for the 50, 60, and 75 GHz O-mode reflectometer system.

• This upgrade simplifies the reflectometer design, and minimizes noise generation arising from multiple ground points.

• New regulator boards designed by C. Kung, PPPL, are used to regulate the voltages to active microwave components such as Gunn Oscillators and mixers.

A new probe head is under fabrication to mount magnetic probes to measure parallel wavenumber of LH waves

Probe Array

• Six magnetic probes will be mounted on a radially moveable probe system.

• Probes were designed at the University of Japan (Takahiro Shinya and Yuichi Takase)

• Vacuum-compatible probes and the probe head are under fabrication.

• The probe head will be mounted on the existing Surface Science Station [R. Ochoukov, MIT PhD Thesis 2013].

• The electronics that will down-convert from 4.6 GHz to 25 MHz have been built.

• Fast speed digitizer (100MS/sec) will directly digitize the signals.

Slit Shield

Digitizer

Spectral MSEWill it work on ITER?

• Spectral MSE• On ITER, may out-perform contemporary spectral MSE

diagnostics due to larger Stark splitting• Suggested as an alternative to standard MSE on ITER

• Alcator C-Mod is uniquely capable of testing spectral MSE at ITER levels of Stark splitting due to large toroidal field

• Proof-of-principle exp was promising: Spectrum yielded pitch angle that is consistent with kinetic E-FIT

• Miniproposal (MP763) approved for experiment with improved optics at ITER-like Stark splitting

In-Vessel Work

• Primary goals• Refurbish plasma facing components and diagnostics• Install new advanced divertor diagnostics• Improve power handling capability of the outer divertor• Diagnostic calibration

In-Vessel Work

• New outer divertor rail probes designed, manufactured, and installed• flush probes should eliminate melting, the most common probe failure

modes• probes extended toroidally to have well-defined projected area,

minimizing effects of sheath expansion on interpretation• Initial results promising, detailed analysis underway

• Divertor heat flux instrumentation refurbished• surface thermocouples now have more reliable triaxial cable• new Langmuir probes installed, modified surface area to meet current

limitations of future divertor mirror Langmuir probe system• Inner divertor Langmuir probes refurbished

• new Langmuir probes installed, replacing melted and shorted probes• new in vessel cabling, replacing damaged cabling

• Inner wall scanning Langmuir probes refurbished• Upper divertor Langmuir probes refurbished

In-Vessel Work

• Lower hybrid launcher Langmuir probes inspected• Limiter retarding field analyzer refurbished• New surface science station ( S3 ) Langmuir probes designed and

manufactured• Limiter and divertor tile thermocouples inspected, repaired where

possible• New servomotor drive upgrade for the horizontal scanning probe system

assembly. Testing underway• Circuit for real time calculation of divertor heat flux from surface

thermocouples for feedback control of impurity seeding designed, built, and tested

• New mirror Langmuir probe system under construction to drive outer divertor Langmuir probes: Will enable feedback control on divertor plasma conditions as well as unprecedented time-resolution of divertor fluctuation measurements

• Polarimeter shutter successfully repaired

In-Vessel Work

• Outer divertor modules have been shimmed to provide a small toroidal twist• All outer divertor modules

were removed, tiles refurbished, shims fitted and modules reinstalled

• Provides a ski jump to reduce heat flux at the edges of the modules

Ski Jump

In-Vessel Work

• New rail probe arrays installed for FY2015 campaign• Power flux density has proved

to be too great for standard button probes

• Rail probes designed to be much more robust (flush to surface)

• High spatial resolution: increased coverage to 21 locations (from 10 previously)

New Rail Probe Arrays

In-Vessel Work

• Three plasma parameters from the probe current-voltage characteristic: electron temperature, ion saturation current, and floating potential

• Plot from one time-slice, each point from an individual probe (scatter due to fluctuations)

• Twice the spatial resolution as previous array allows for finer spatial resolution without strike point sweeps

Initial Rail-Probe Profile Data

Short Term Schedule

• Planning for 12 weeks of research operation in FY2015• Currently completing plasma conditioning phase of operation

ID Task Name Duration Start Finish1 Pumpdown 0 days Fri 4/17/15 Fri 4/17/152 Leakcheck/Bake/ECDC 11 days Sat 4/18/15 Tue 4/28/153 Plasma Condition 15 days Wed 4/29/15 Fri 5/22/154 Plasma Ops FY2015 20 days Tue 5/26/15 Fri 6/26/155 Maintenance 8 days Mon 6/29/15 Thu 7/9/156 Plasma Ops FY2015 20 days Fri 7/10/15 Thu 8/13/157 Maintenance 9 days Fri 8/14/15 Wed 8/26/158 Plasma Ops FY2015 20 days Thu 8/27/15 Wed 9/30/15

Mon 11/16/15 Fri 11/20/15

9

10 APS Meeting (2015) 5 days111213

4/17

12 Weeks

March 2015 April 2015 May 2015 June 2015 July 2015 August 2015 September 2015 October 2015 November 2015

Mon 5/18/15

C-Mod Well Represented at SOFE (May 31st to June 4th Austin, Texas)

Invited Talk (Plenary)

Smaller & Sooner: Exploiting New Technologies for Fusion's DevelopmentD. Whyte

Invited Talks

Alcator C-Mod and ADX: Research on the High-Field Pathway to Fusion EnergyB. LaBombard

RF Enabling Technologies for Reactor Relevant DevicesS. J. Wukitch, P. T. Bonoli, Y. Lin, G. Wallace, S. Shiraiwa, S. G. Baek, R. R. Parker, W. M. Beck, R. Vieira

Engineering the Alcator C-Mod MSE Diagnostic: Solutions to Reactor-Relevant Diagnostic ChallengesR. T. Mumgaard, S. D. Scott

The Engineering and Operation of AIMS, an In-Situ Accelerator-Based Diagnostic for Plasma Facing ComponentsZ. S. Hartwig, H. S. Barnard, B. N. Sorbom, L. A. Kesler, W. M. Burke, J. Doody, R. C. Lanza, P. W. Stahle, D. R. Terry, R. F. Vieira, D. G. Whyte, L. Zhou

Vulcan

SOFE

Papers and Posters

Analysis of ICRF Ferrite TunerP. Koert, L. Zhou, S. Wukitch, A. Binus, E. Fitzgerald, A. Pfeiffer, R. Murray

RF, Disruption and Thermal Analyses of East AntennasL. Zhou, W. K. Beck, P. Koert, Q. X. Yang*, C. M. Qin*, X. J. Zhang*, J. Doody, R. F. Vieira, S. J. Wukitch, R. S. Granetz, J. H. Irby, Y. P. Zhao**Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, P.R. China

The Engineering Design of ARC: A Compact, High Field, Fusion Nuclear Science Facility and Demonstration Power PlantB. N. Sorbom, J. Ball, T. R. Palmer, F. J. Mangiarotti, J. M. Sierchio, P. Bonoli, C. Kasten, D. Sutherland, H. S. Barnard, C. B. Haakonsen, J. Goh, C. Sung, D. G. Whyte

Power Systems Analysis and Design for ADXD. R. Terry, J. Irby, W. Cochran, S. Wolfe, B. LaBombard, W. Burke, R. Vieira

Structural Analysis of High-Field-Side Rf Antennas During a Disruption on the Advanced Divertor Experiment (ADX)J. Doody, B. LaBombard, R. Leccacorvi, S. Shiraiwa, R. Vieira, G. M. Wallace, S. J. Wukitch, J. H. Irby

Novel Vacuum Vessel & Coil System Design for the Advanced Divertor Experiment (ADX)R. F. Vieira, J. Doody, W. K. Beck, L. Zhou, R. Leccacorvi, B. LaBombard, R. S. Granetz, S. M. Wolfe, J. H. Irby, S. J. Wukitch, D. R. Terry, G. M. Wallace, R. R. Parker ADX

SOFE

Papers and Posters

High Field Side Launch of Lower Hybrid Waves: a Scoping Study for ADXG. M. Wallace, S. Shiraiwa, S. G. Baek, P. T. Bonoli, A. D. Kanojia, P. Koert, B. L. LaBombard, R. Leccacorvi, R. R. Parker, D. R. Terry, R. Vieira, S. J. Wukitch

Advanced ICRF Antenna for ADXS. J. Wukitch, P. T. Bonoli, Y. Lin, W. M. Beck, R. Vieira

Real-Time High-Field Measurement of Joint Resistance in the Alcator C-Mod Toroidal Field MagnetW. M. Burke, A. Kanojia, J. A. Stillerman

The Shoelace Antenna: a Device for Inductively Coupling to Low Frequency, Short Wavelength Fluctuations in the Plasma BoundaryT. Golfinopoulos, W. M. Burke, B. LaBombard, R. R. Parker, W. C. Parkin, P. P. Woskov

28

~5cm

High Field Launcher Design

Shoelace Antenna

EOT

C-Mod FY2015 run planning

presented by R. Granetz

Alcator C-Mod quarterly review 2015/05/20

C-Mod FY2015 operation

• Budgeted for 12 research run weeks (48 physics run days)

– Next year’s (FY2016) guidance budget provides for a maximum

of 5 weeks of operation, and then C-Mod is scheduled to cease

operation, so there is intense pressure on run time

• Plan to devote much run time to topics that C-Mod is

uniquely capable of addressing, including:

– High B-field (8 tesla)

– High performance I-mode

– Lower hybrid (2015 JRT is on off-axis current drive)

– ICRF field-aligned antenna

• 56 run days’ worth of highest priority experiments are

competing for run time

2/4

C-Mod FY2015 highest

priority run days requested

Topic/Group Run Days

----------- ------------

Transport 10.5

Pedestal 12.6

Boundary 11.5

LH 4.0

ICRF 6.0

MHD/Disruptions 5.0

ITER specific requests 6.4

(not included in other topics)

----- ----

Total research days for 56.0 (14.0 weeks)

highest priority experiments

Research target for FY2015 is 12 weeks.

NOTE: This does not include 38.0 other high

priority run days requested

3/4

C-Mod operations:

current status

Late April — pumped down; baked out

04/29 to 05/22 — plasma startup, conditioning, discharge cleaning,

ICRF conditioning, LH conditioning

Week of 05/26 — boronization; recovery

06/01 — begin physics research operations

June - Sept — three run blocks of 4 weeks each, with two

maintenance periods interspersed (~1.5 weeks each)

• First run block has B drift downward

• Plan to switch field & current direction later in campaign

(for I-mode studies and relativistic electron studies)

4/4

DIII-D: Subcontract status and research plans

J. Hughes on behalf of the C-Mod Team

C-Mod Quarterly Review 20 May 2015

GA subcontract for MIT research on DIII-D: Timeline

• 2013: Subcontract negotiations began with intent of funding research in FY14

• 11/2013 – 1/2014: Work was performed under GA-MIT Letter Agreement, while final subcontract being negotiated

• 1/2014: Subcontract put on hiatus following passing of FY14 appropriations

• 10/2014: Discussions re-opened on subcontract

• 11/2014: MIT and DIII-D research contacts began communicating on potential projects, key personnel

• 4/2015: Scope of subcontract, deliverables agreed upon by MIT + DIII-D technical staff

• Currently:

– GA Statement of Work (SOW) is in management approval stage

– RFP is expected to go to MIT in 1—2 weeks

– MIT proposal will be submitted 1—2 weeks after receipt of RFP

– MIT is prepared to resume subcontract funded collaboration on DIII-D soon after

C-Mod/DIII-D Collaboration Status, 22 Jan 2015 1

MIT and DIII-D have agreed on scope of proposal (4/22)

• Multi-channel turbulent transport in the tokamak core (D. Ernst, N. Howard, A. White)

– Experimental emphasizing impurity, momentum, electron energy transport

– Diagnostic development; Simulation and model validation

• Pedestal physics in high-performance ELM-suppressed regimes (J. Hughes, J. Walk)

– Characterization + modeling of recent and proposed QH-mode, I-mode experiments

• Disruption prediction and warning (R. Granetz)

– Disruption warning algorithm development for implementation in DIII-D PCS

• Development and delivery of RF hardware to optimize plasma performance (S. Wukitch)

– Design, engineering and fabrication of hardware for high-power helicon antenna

– Participate in installation on DIII-D (2016)


Subcontract work prelude to enhanced DIII-D collaboration

• Near-term work is a beginning to larger collaboration as outlined in MIT 5-year proposal (in review)

• Sub-contract will allow near-term addition of

– 3 FTE of PSFC staff to DIII-D research

– 2 new MIT postdocs (on-site at DIII-D)

– 2—3 MIT graduate students

• Themes and topics align between near-term and long-term proposals, with significant expansion after 2016


Signing subcontract will enable and accelerate DIII-D collaboration

• Transport:

– Darin Ernst has been nominated for a 2015 APS-DPP invited talk on DIII-D research into TEM turbulence


• Disruption warning:

– SQL database initiated for identification of DIII-D disruptions, similar to those developed for C-Mod and EAST

– Intent is to develop disruption prediction algorithms

• Helicon hardware

– Specifications have been determined for coaxial vacuum feedthroughs, transition components

– Cost of fabrication being determined: DIII-D funds will be added to the subcontract to cover these additional costs

Histogram of current quench time for DIII-D

disruptions (1999-present)

--R. Granetz

International Collaboration on Control and Extension of ITER

and Advanced Scenarios to Long Pulse in EAST and KSTAR

P. T. BonoliOn behalf of the MIT Team:

S. G. Baek, R. S. Granetz, E. Edlund, A. E. Hubbard, Y. Lin, R. R. Parker, M. Porkolab, J. E. Rice, S. Shiraiwa, J. Stillerman,

G. M. Wallace, and J. C. Wright

DoE TeleconferenceMay 20, 2015

Task 1: Extension of the I-Mode scenario to EAST & KSTAR

• EAST (A. Hubbard; X. Gao, T. Zhang, Z. X. Liu, G. Q. Li, Y. Yang, D.F. Kong, and X. Han):– An experimental proposal for “Development and study of I-mode on

EAST” was revised and submitted in January 2015.– Anticipate scheduling for next physics campaign; Hubbard is making

plans to participate on site.– This will include current, density and power scans, and also the novel

idea of adding RMP coils to increase particle transport.• KSTAR (A. Hubbard & J. Ko):

– Initial attempts in October, 2014 to produce I-mode were unsuccessful due to problems with position control in USN configuration (drsep and inner gap).

– Will try again in 2015 when KSTAR starts up.– PCS work by GA as part of this collaboration will assist the KSTAR

team in resolving these issues so that experiments in 2015 can provide more definitive results.

Task 2. Long Pulse Disruption Free Control

• Primary activity has been the installment of a disruption database on EAST, which is now fully functional and automatically populated with new disruptions.

• Studies of relativistic runaway electrons (RE's) during disruptions on EAST (R. Granetz): – Working with one of the EAST physicists who is studying this on

EAST.– Planning to visit EAST this summer while they are operating in order

to participate in some of the RE experiments.– At ASIPP, Granetz is working with several graduate students who are

doing disruption-related research. – One student is developing disruption prediction/warning algorithms

based on neutral networks. – Granetz will be hosting this student during a month-long visit to MIT

in August/September at the request of his advisor, Jiangang Li.

Task 3. Diagnostic and Actuator Development for Scenario Extension

• Mode conversion flow drive (MCFD) studies on EAST with an ICRF actuator (Y. Lin, Xinjin Zhang, Jiale Chen):– Submitted a mini-proposal to perform (MCFD) experiments on EAST.– Y. Lin (MIT) worked with Xinjun Zhang and Jiale Chen, on including TORIC

ICRF simulation results into an ICRF MCFD calculation by J. Chen [J. Chen and Z. Gao, Phys. Plasmas 21, 062506 (2014) and Z. Gao, J. Chen and N.J. Fisch, Phys. Rev. Lett 110, 235004 (2013)].

– Chen's theoretical work has shown some qualitative agreement with C-Mod MCFD results, and his theory will be used to guide EAST research in MCFD.

– Y. Lin is planning a trip to EAST in summer 2015 (likely in July), to participate in ICRF work in general and MCFD research on EAST with a possible second trip to EAST in combination with ITPA-IOS meeting in October.

• ICRF coupling and absorption studies for EAST (E. Edlund, S. Wukitch, M. Porkolab):– E. Edlund has been using the TORIC ICRF solver to perform simulations for a

new four strap antenna to project the k// needed for optimal coupling (E. M. Edlund, P. Bonoli, M. Porkolab, S. J. Wukitch, paper at the 21st Topical Conference on Radio-frequency Power in Plasmas, 27-29 April 2015, Lake ArrowHead, CA).

Task 3. Diagnostic and Actuator Development for Scenario Extension

• Simulation studies of LHCD in EAST (S. Shiraiwa, P. T. Bonoli, J. C. Wright; Boijang Ding, Miaohui Li, Cheng Yang):– Using GENRAY / CQL3D can reproduce the peaked hard x-ray and current

density profiles in EAST experiments by slightly broadening the incident LH power spectrum (5% of power put in a lobe at n// = 2.75).

– Same approach has been used to successfully simulate C-Mod LHCD experiments [S. Shiraiwa, Invited Talk at the 21st Topical Conference on Radio-frequency Power in Plasmas, 27-29 April 2015, Lake ArrowHead, CA)].

– EAST simulation studies also being carried out now in collaboration with Y. Peysson from CEA / IRFM using the LUKE / C3PO model.

• Plan to participate in LHCD Physics experiments on EAST in 2015:– Perform experiments to examine source frequency dependence of LHCD (2.45

GHz vs. 4.6 GHz) as a function of density by monitoring PDI and hard x-ray emission (S. Baek, R. Parker).

– Study poloidal dependence of LHCD by separately powering off mid-plane rows of 4.6 GHz LH launcher (R. Parker, G. Wallace).

– Continue analysis of LHCD experiments using GENRAY / TORLH / CQL3D.

International Collab: Development of long-pulse RF actuators and Operational Techniques for High Z PFC

Plasma operations expected from midJune to end of August.• Under vacuum since end of April

• Repaired tungsten divertor.

• Second 4 MW of NBI has been installed.

• ECRF is limited to 0.5 MW per gyrotron(~1 MW source) for coming campaign.

Campaign planning:• Number of proposals submitted by EAST

deadline (27 January).

• Had internal planning meeting 5/15-17.

Wukitch - DoE Quarterly 20150520 1

Overall campaign goals are:• Develop long-pulse/steady-state, high performance scenario with a low

momentum input and

• Develop long-pulse (>100s) scenario with a high electron temperature (>4.5keV).

For EAST ICRF, Improving Coupling is Critical

EAST antenna coupling has low couplingefficiency.

Antenna coupling efficiency is estimatedby . ||


0.0 0.2 0.4 0.6 0.8 1.0r/a

0

1

2

3

Elec

tron

Den

sity

[m-3

x10

19]

Cutoff Density ~9x1018 m-3

2.3 T, Ip= 373 kA, 48888

Operate 4 strap antenna in current drive [0,] and /3 phase[0, ] to improve coupling efficiency.• CD phase – k||=7.2 m-1 , necut~2.2x1018 m-3, and =0.53.• /3 phase – k||=4.8 m-1, necut~1x1018 m-3, and =0.65.

For new antenna, attempt to minimize k|| while maintaining good SPA.• An experimental proposal to investigated antenna loading versus antenna phase

is planned for the upcoming campaign.

I port antenna:k||=14.4 m‐1 and necut~9x1018 m‐3

x~8 cm=0.28

B port antenna:k||=12.6 m‐1 andnecut~6.4x1018 m‐3.x~8 cm=0.33

C‐Mod:k||=11 m‐1and 14 m‐1

necut~5x1018 m‐3

x~2 cm~0.75

Core Absorption: High Single Pass Absorption for H Minority

• 100 keV is typical minority ion energy.

For reference, we show C-Mod values - which have demonstrated highheating efficiency.• For k||=4.8 m-1, the single pass absorption is similar to C-Mod conditions and

expect good absorption.• For k||=9 m-1, single pass absorption is approaching 40% for 1 keV plasma.


1.0 keV

5.0 keV

10.0 keV

100.0 keV

0 5 10 15 20nH/ne (%)

0

20

40

60

80

100

Sing

le p

ass a

bsor

ptio

n (%

)

10.0 keV

5.0 keV

C-Mod k||=10 m-1

EAST k||=4.8 m-1

EAST k||=9 m-1

Estimate minority H heatingscenario single passabsorption with analyticformula and includeimpact of energetic ions.• 1 keV and 5 keV curves

represent thermal plasmasingle pass absorption.

• 10 keV tail shows howquickly the minorityenergy impacts singlepass aborption.

EAST Conceptual FA Antenna: General Specifications

ICRF antenna power capability: 4.2 MW into ELMy H-modeBandwidth: 30-70 MHz transmitter bandwidth

• 2.5 T operation H minority is 38 MHz, 2nd harmonic is 76 MHz• 3 T operation H minority cyclotron frequency = 45.6 MHz

Maximum average electric field is not to exceed 15 kV/cm where E||B.• Maximum voltage 45 kV.

Mechanical stress based upon disruption: 0.2 MA/s @3.5 TBake out temperature: 300° CPreferred antenna strap configuration is end fed, center grounded

• RF antenna limiter: 2.355 m• 5 mm behind plasma limiter

Antenna to operate 100 s.• Current straps, Faraday shield and protection tiles to be actively cooled.• Coolant: water• Coolant pressure: 3 atm• Coolant flow velocity: 2 m/s


Current Strap Layout for Conceptual EAST FA Antenna

Antenna straps are to normal to total magneticfield, field line pitch is 7°.

Current strap is end fed-center grounded.• Strap length 700 mm• I and B antenna straps are ~640 mm.

Current straps are 350 mm on center.• Corresponds to k||~9 m-1.• Coupling efficiency ~45% assuming distance to

cutoff is unchanged.• necut~4x1018 m-3 – bottom of pedestal

Antenna is to replace I port antenna.• Antenna structure will occupy wall space

between H and J port without interfering with Hor J port.

• Limits strap spacing; thus coupling efficiency.


For end fed/center grounded, coaxial to strip linefeeds are a challenge.

If the feedthrus are moved closer to the backplate, new feedthrus will be required.• Design will be similar to the feedthrus used on the

C-Mod FA antenna.• Position coax feeds to maximize clearance

between neighbors.

Work was presented at 21st Top. Conf. on RFPower in Plasmas 2015.

Vacuum Transmission Line Behind Back Plate


Summary of Activity: Divertor/Disruptions

We worked with EAST onunderstanding where divertorcooling channel leaks arelocated and investigate acause.• Failure of connection pipes

occurred during machine bakeout.

• Cluster of failures at the interfaceblock may be related to poorelectron beam welds from one oftwo manufacturers.


Four Chinese visitors were here to review tungsten divertor and discussplans for hot tungsten divertor.

Presented fully aligned and hot divertor designs for C-Mod.• Major challenge for EAST hot divertor design is thermal expansion.• EAST divertor is fixed at 3 locations that prevent expansion.

Summary of Activity: Disruptions

Integrated filament reconstruction is available.• Correct geometry and input/output data stored in MDS trees.• Critical to engineering studies on divertor electromagnetic studies.• Request for 7000 existing discharges prompted ICRF group to properly evaluate

and store RF power signals in central repository.

Work on disruptions (Bob Granetz) has been published in Chinese PhysicsB.• Characterization of plasma current quench during disruption in EAST

tokamak• Work is based on the disruption database (first sql database at EAST)

implemented by Granetz.• Utilizes MFIL for flux surface reconstruction during disruption (Granetz

contribution).

Bob Granetz visited EAST in March.Proposed experiments on disruptions and runaway electron physics for

upcoming campaign.


Summary of Activity: Low P regimes (I-mode)

Dr. Zixi Lui (ASIPP Postdoc) has started BOUT++ analysis of C-Mod I-modes, in collaboration with X. Xu (LLNL) and C-Mod.• MIT supplied equilibrium and pedestal profiles for a well diagnosed, high

confinement discharge.

Simulated turbulence using progressively more complete physics inBOUT++• 3-field, linear simulations confirmed the expected peeling ballooning stability,

consistent with lack of ELMs.• Linear simulations indicated that I-mode turbulence likely has contributions from

both drift Alfven waves and ballooning modes.• Full nonlinear simulations have recently been done which show fluctuation

spectra quite similar in location, frequency and wavenumber to measurements ofthe weakly coherent mode.

• Simulations show that particle diffusivity from these fluctuations is larger thanthermal diffusivity, which is close to the experimental value

Work was presented at EU-US Transport Task Force meeting in May 2015.An experimental proposal for “Development and study of I-mode on EAST”

is planned for the upcoming campaign.


Documents

Facility Status - Massachusetts Institute of Technology · *Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, P.R. China The Engineering Design of ARC: A Compact,