Summary of RF-Related Presentations at Summary of RF-Related Presentations at the 2011 EPS Meetingthe 2011 EPS Meeting

G. Taylor

NSTX Physics MeetingJuly 25, 2011

NSTXNSTX Supported by

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Summary of RF Presentations at EPS (Taylor) July 25, 2011NSTXNSTX NSTX Physics Meeting

Overview of EPS RF Presentations Overview of EPS RF Presentations

• Alexander Litvak, Keishi Sakamoto and Manfred Thumm were awarded the 2011 EPS Innovation Prize for developing high-power, long-pulse gyrotrons:

Thumm presented a talk on the development of MW-class CW gyrotrons at 140 and 170 kW for W-7X and ITER

Strong multi-decade collaboration on high power gyrotron development between Russia, Japan, Europe and US [No US prize winner?]

• Approximately 30 presentations on RF coupling, heating and current drive (CD) physics:

Not including presentations that used RF heating & CD primarily to study transport, MHD stabilization, etc…[Some covered by Steve Sabbagh]

Presentations covered ion cyclotron, lower hybrid, electron cyclotron and electron Bernstein wave coupling, heating and CD

I'll comment on a few presentations in each frequency range

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Summary of RF Presentations at EPS (Taylor) July 25, 2011NSTXNSTX NSTX Physics Meeting

ICRF Presentations - IICRF Presentations - I

• E. Lerche presented an invited talk on JET ICRF experiments and modeling relevant to BT ~ 2.65 T ITER low-activation phase [I5.012]:

H heating in H plasmas has =30-40%, requires high temperature plasma

23He heating in H(3He) plasmas has =15-40%, increasing with 3He concentration

H heating in 4He(H) plasmas has ~70% for H concentration <25%

Results consistent with modeling predictions

• A. Lyssoivan [P4.060] presented modeling results for JET Ion Cyclotron Wall Conditioning (ICWC) experiments and predictions for ICWC in ITER:

Predicts excitation of a vacuum TM cavity mode with an on-axis Ez field maximum in an ITER-like torus at 43-44 MHz

May result in simultaneous breakdown and ionization over the ITER torus

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Summary of RF Presentations at EPS (Taylor) July 25, 2011NSTXNSTX NSTX Physics Meeting

ICRF Presentations - IIICRF Presentations - II

• D. Green [P1.103] presented L-mode and H-mode NSTX HHFW modeling results using 3-D AORSA with realistic wall geometry:

Predicts a strong RF-excited edge modes at long launch wavelength that are sensitive to the edge density profile

• R. Harvey [P4.017] presented results for NSTX NBI and NBI+HHFW plasmas using a new first order finite-orbit-width (FOW) correction to ion Fokker-Planck modeling in CQL3D:

Much better agreement with FIDA data for NBI plasma Outward shift is much bigger than measured by FIDA for NBI+HHFW,

probably because FOW correction over estimates shifts that are ~ plasma radius

Major Radius (cm) Major Radius (cm)

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Summary of RF Presentations at EPS (Taylor) July 25, 2011NSTXNSTX NSTX Physics Meeting

LHRF Presentations - ILHRF Presentations - I

• V. Dyachenko [P4.098] presented results using LH to start-up, ramp-up and sustain a plasma non-inductively in Globus-M:

Used 100 ms, 100 kW pulses of 920 MHz RF from two comb-line antennas RF breakdown occurred near the antenna surface

Antenna with broad symmetrical spectrum produced Ip ~ 17 kA

Progress depends on understanding the electron acceleration mechanism

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Summary of RF Presentations at EPS (Taylor) July 25, 2011NSTXNSTX NSTX Physics Meeting

LHRF Presentations - IILHRF Presentations - II

• M. Goniche [P1.102] reported on experiments that studied the density dependence of LHCD efficiency in Tore Supra:

Plasma edge and SOL were varied Degradation in LHCD efficiency is strongly correlated with enhanced density

fluctuations in the SOL near the antenna

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Summary of RF Presentations at EPS (Taylor) July 25, 2011NSTXNSTX NSTX Physics Meeting

EC/EB RF Presentations - IEC/EB RF Presentations - I

• Y. Peysson [I1.104] presented an invited talk on radial broadening of the EC and LH RF power absorption due to plasma fluctuations:

Used C3PO ray tracing code and the LUKE 3-D Fokker-Planck solver Significant broadening predicted for 170 GHz first harmonic O-mode

ECH in ITER, even with fluctuations localized near the edge Much less effect for second harmonic X-mode ECH in ITER Plasma fluctuations generally only weakly degrade CD efficiency

• J. Stober [I5.117] reported on second harmonic O-mode (O2) and third harmonic X-mode (X3) heating schemes in ASDEX-U and their application to fusion reactors:

Essential for H-mode operation with W walls, controls central W accumulation X2 resonance at high field edge acts as beam dump for X3 heating scheme Holographic mirrors developed to allow a second pass with O2 heating

• E. Gusakov [P4.101] presented modeling results that predicted high power ECRH, at power levels similar to those planned for ITER, may generate PDI that that could reduce ECCD efficiency

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Summary of RF Presentations at EPS (Taylor) July 25, 2011NSTXNSTX NSTX Physics Meeting

EC/EB RF Presentations - IIEC/EB RF Presentations - II

• A. Kohn [P2.020] reported on the effect of fluctuations on O-X-B coupling in TJ-II:

2-D full wave simulation with a 10% density fluctuation predicts a significant scattering of wave electric field and reduction in O-X-B coupling from 86%60%

• T. Stange presented a contributed oral [O3.114] and poster [P5.094] on multi- frequency heating and CD in WEGA stellarator :

A high density (>1020m-3) heating scenario that combined of 28 GHz O-X-B heating and 2.45 GHz LHCD proved beneficial

28 GHz EC plasma startup generates seed electrons for 2.45 GHz LH damping

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Summary of RF Presentations at EPS (Taylor) July 25, 2011NSTXNSTX NSTX Physics Meeting

EC/EB RF Presentations - IIIEC/EB RF Presentations - III

WEGA LH/EC heating scenario characterized by generation of > 1 MeV electrons that strongly deviate from magnetic surfaces

As the density increases the plasma becomes overdense resulting in O-X-B heating:

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