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NSTX. Supported by. Summary of RF-Related Presentations at the 2011 EPS Meeting. G. Taylor NSTX Physics Meeting July 25, 2011. Overview of EPS RF Presentations.
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NSTX Supported by Summary of RF-Related Presentations at the 2011 EPS Meeting G. Taylor NSTX Physics Meeting July 25, 2011
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
ICRF 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]: • WH heating in H plasmas has h =30-40%, requires high temperature plasma • 2W3He heating in H(3He) plasmas has h =15-40%, increasing with 3He concentration • WH heating in 4He(H) plasmas has h ~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
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) Major Radius (cm)
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 Ip ~ 17 kA • Progress depends on understanding the electron acceleration mechanism
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
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
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 (>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
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: