Summary of RF-Related Presentations at the 2011 EPS Meeting G. Taylor NSTX Physics Meeting July 25, 2011 NSTX Supported by 1

Summary of RF Presentations at EPS (Taylor) July 25, 2011 NSTX NSTX Physics Meeting 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 2

Summary of RF Presentations at EPS (Taylor) July 25, 2011 NSTX NSTX Physics Meeting ICRF Presentations - I E. Lerche presented an invited talk on JET ICRF experiments and modeling relevant to B T ~ 2.65 T ITER low-activation phase [I5.012] :   H heating in H plasmas has  =30-40%, requires high temperature plasma  2  3 He heating in H( 3 He) plasmas has  =15-40%, increasing with 3 He concentration   H heating in 4 He(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 E z field maximum in an ITER-like torus at MHz  May result in simultaneous breakdown and ionization over the ITER torus 3

Summary of RF Presentations at EPS (Taylor) July 25, 2011 NSTX NSTX Physics Meeting ICRF 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) 4

Summary of RF Presentations at EPS (Taylor) July 25, 2011 NSTX NSTX Physics Meeting LHRF 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 I p ~ 17 kA  Progress depends on understanding the electron acceleration mechanism 5

Summary of RF Presentations at EPS (Taylor) July 25, 2011 NSTX NSTX Physics Meeting LHRF 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 6

Summary of RF Presentations at EPS (Taylor) July 25, 2011 NSTX NSTX Physics Meeting EC/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  7

Summary of RF Presentations at EPS (Taylor) July 25, 2011 NSTX NSTX Physics Meeting EC/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 (>10 20 m -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 8

Summary of RF Presentations at EPS (Taylor) July 25, 2011 NSTX NSTX Physics Meeting EC/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: 9