Tuomas Tala Tekes Annual Seminar 2010 - VTT...VTT TECHNICAL RESEARCH CENTRE OF FINLAND 4 Association Euratom–Tekes TBM Mock-up on DIII-D Tokamak ¾Matches ITER TBM far magnetic field

AssociationEuratom–Tekes

ITER Test Blanket Module Experiment (TBM) on DIII-D Tokamak in San Diego

T. Tala1 and the TBM International Team and DIII-D Team

1VTT, P.O Box 1000, FI-02044 VTT

VTT TECHNICAL RESEARCH CENTRE OF FINLAND2


The TBM Experiment International TeamComprised All the 7 ITER Parties

• Joseph Snipes ITER• Naouki Oyama Japan• Kouji Shinohara Japan• Hogan Jhang S Korea• Kwang-Il You S Korea• Xiang Gao China• Songlin Liu China• Yanjing Chen China• Guoyao Zheng China• Gabriella Saibene Europe• Antti Salmi Europe• Tuomas Tala Europe• Peter de Vries Europe• Vladimir Pustovitov Russia• N Submarian India• Don Spong USA• David Gates USA• Jong-Kyu Park USA



Introduction

ITER TBM experiments performed on DIII-D from November 11-20, 2009– 6.5 experimental days (8:00 - 20:00 tokamak operation)– 254 plasma shots (over 90% useful plasma discharges)

Experiments planned and performed by the International TBM team comprised of scientists from the 7 ITER partners and the ITER organization with on-site and remote participation. Unique tokamak physics experiment triggered by the ITER team and including all ITER parties.

Main experimental objectives: Determine the effects of the TBM mock-up on various plasma properties to be able to extapolate to ITER

– H-mode threshold and performance (confinement, pedestal, Edge Localised Modes ELMs, rotation, etc.)

– ELM suppression by resonant magnetic perturbations– Locked modes and TBM error field correction– Fast ion transport



TBM MockTBM Mock--up on DIIIup on DIII--D D TokamakTokamak

Matches ITER TBM far magnetic field− Too narrow to match near field

in detail

Moveable, ∆R ≥ 1.0 ‘ITER meter’− To model TBM recession

Mockup capable of ~3x ITER ∆B/B0− To match surface-average amplitude of 6

ITER TBMs− Cannot match ITER’s 6-TBM spectrum

Mock-up was set to various distances from plasma

– Recession

TBM mock-up removed after the experiments and can be put back if needed

Racetrack coils ⇔ Bφ (toroidal magnetisation)Vertical solenoid ⇔ Bθ (poloidal magnetisation)

TBM coil assembly fits into available DIII-D portCourtesy of M. Schaffer



DIII-D TBM Mock-up Field Narrower than the ITER One

DIII–D Mockup Field at DIII-D plasma surface

ITER TBM Field at ITER plasma surface

BTOR, BR, BZBTOR, BR, BZ

Note that DIII-D and ITER have different magnetic handedness

-200 -100

200

00

400

Z (m)Z (m)0 +2 0 +1-1 -1

gauss gauss

800



Main results from the DIII-D TBM experiments



TBM Does Not Affect the H-mode Power ThresholdVery important and positive result for ITER!

L-mode L-modeH-mode H-mode



The Effect of TBM Modest on Density and Pressure

TBM causes a reduction of around 10% in density and pressure (betan) and consequently energy at the expected ITER TBM perturbation field

Time (ms)

~10% ~10%

~10%~10%



The Largest Effect of TBM Is Observed on Plasma Rotation

Toroidal rotation profile

Plasma rotation drops after TBM switch on, reduction up 80%

confinement

pressure

rotation

Rot

atio

n



The TBM Has No Discernible Impact on ELM (Edge Localised Mode) Suppression by Resonant Magnetic Perturbations (Planned Also in ITER)

ELM suppression coil

Signature of ELMs



Reduction in the Density, Beta, Confinement Factor and PlasmaRotation with Increasing TBM Current (Local Ripple)

(Local ripple caused by TBM in brackets, %)

Density reduction

Pressure reduction

Confinement reduction

Rotation reduction



The Effects of the TBM Are Decreased by Recessingthe TBM Further from the Plasma

Relative changes in density, pressure, confinement and rotation all decrease with recessed distance —still ~5% at furthest distance

Recessing TBM by 15 cm decreases the effects of TBM by 3–4 times (local ripple in brackets, %)

Density reduction Confinement reduction

Pressure reduction Rotation reduction



Conclusions

TBM experiments carried out successfully by the International Team comprising of all 7 ITER parties, including very strong participation by Tekes AssociationThese results provide a robust base for the final ITER TBM design (discussed widely in the TBM workshop organised in ITER in April 2010)The TBM ripple has no significant effect on the H-mode power thresholdThe TBM ripple affects the confinement properties of H-mode plasmas

– most significant effect is observed on plasma toroidal rotation with decreases of up to 80%– confinement times, beta and density (plasma performance) exhibit smaller reduction of 5-15%

Rotation reduction appears to be characteristic of a non-resonant braking torqueThe TBM ripple has no significant effect on the ability to suppress ELMs by resonant magnetic perturbationNo convincing indications of increased global fast ion loss fraction due to TBM

– consistent with numerical modelling (ASCOT modelling on-going here by Tekes Association)

Documents

Tuomas Tala Tekes Annual Seminar 2010 - VTT...VTT TECHNICAL RESEARCH CENTRE OF FINLAND 4 Association Euratom–Tekes TBM Mock-up on DIII-D Tokamak ¾Matches ITER TBM far magnetic field