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HHFW Current Drive, RF-Only H-modes, and HHFW+NBI

HHFW Current Drive, RF-Only H-modes, and HHFW+NBI. presented by Phil Ryan (ORNL) for J. Hosea, B. Leblanc, R. Pinsker, D. Swain, J. R. Wilson, and the NSTX HHFW Team. NSTX Results Review Sept 20, 2004. HHFW Operation in 2004. Developed DND HHFW plasma scenarios

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HHFW Current Drive, RF-Only H-modes, and HHFW+NBI

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  1. HHFW Current Drive, RF-Only H-modes, and HHFW+NBI presented by Phil Ryan (ORNL) for J. Hosea, B. Leblanc, R. Pinsker, D. Swain, J. R. Wilson, and the NSTX HHFW Team NSTX Results Review Sept 20, 2004

  2. HHFW Operationin 2004 • Developed DND HHFW plasma scenarios • Separate plasma fueling from antenna coupling • Center stack gas injector and DND geometry • Operated with rtEFIT control of plasma position. • Installed Langmuir probes at antenna array. • Extended HHFW CD to higher density, DND plasmas (XP403). • HHFW Driven H-mode plasma operational envelope expanded (XP425 - Leblanc) • Combined HHFW-NBI operation (XP413 - Leblanc) • ERD measurements show ion heating in peripheral region

  3. cntr-CD co-CD HHFW on HHFW CD at kz = 7.6 m-1 • Operation at 30% higher density gave DICD ~ 100 kA for DP = 4.2 MW (2.7 MW co-CD, 1.5 MW cntr-CD). • Te(0) = 1.7 keV, ne(0) = 2.1x1019 m-3, He, double-null diverted, Ip = 0.5 MA, 0.45 T. Stored Energy and RF Power Loop Voltage (corrected for dI/dt) Ryan NSTX Results 2004

  4. HHFW CD efficiency, referenced to total antenna power, is somewhat lower than predicted • CD efficiency lower than predicted by CURRAY ray-tracing code (Mau) and slightly lower than AORSA full-wave code (Jaeger). • Density-normalized current drive efficiency same as at lower densities in D and He (g = 0.03 x 1019 A•m-2•W-1) • Double-null and single-null diverted configurations give similar efficiencies. Te(0) = 2 keV kz = 7.6 m-1 CURRAY AORSA D He 2002 2003 2004 Ryan NSTX Results 2004

  5. HHFW operation at kz = 3 m-1 failed to heat central electrons • CURRAY and AORSA calculations predict greater current drive efficiency for Te(0) ~ 2 keV. • Plasma was pre-heated to Te(0) ~ 2 keV with 2.5-3 MW of HHFW for 100 ms at -90º phasing (-7.6 m-1). • Fast switching to 1.7 MW at -30º (-3 m-1) caused a rapid collapse of Te and an increase in <ne>. RF Power (MW) RF Power (MW) RF Power (MW) Ryan NSTX Results 2004

  6. Density Contours From Reflectometer -90º -30º Onset of rf steepens edge profiles Phase shift has little effect on edge profile

  7. Driven H-mode and NBI-Combined Heating SummaryPreliminary Data - Leblanc • HHFW Driven H-mode plasma operational envelope expanded • Ip ≈ 0.6-0.8 MA, BT ≈ 0.45 T, medium density DND • k// = 14 and 7 m-1 at Ip = 0.6 MA • k// = 14 m-1 at Ip = 0.8 MA • Combined HHFW-NBI operation • Developed 2-beam reduced energy scenario compatible with HHFW antenna operation • NBI into HHFW pre-heated plasmas • Wmhd and neutron rate increases observed • Low efficiency • HHFW into NBI-drive H-mode plasmas • Wave do no seem to reach plasma core BPL-NSTX-Res-Sep-2004

  8. HHFW H-mode at 0.7 MAHHFW with beam blips,k// = 14 m-1, 1.5 MW BPL-NSTX-Res-Sep-2004

  9. HHFW Driven H-mode at 0.8 MAHHFW only, k// = 14 m-1, 2.0 MW BPL-NSTX-Res-Sep-2004

  10. NBI Pulses into HHFW Heated PlasmaObserved Wmhd and Neutron (Sn) Increases Sn increase larger than for Wmhd BPL-NSTX-Res-Sep-2004

  11. HHFW into NBI Driven H-mode PlasmaSmall Effects On Wmhd and Neutron (Sn) Are Reproducible Seem more compatible with edge effects than heating BPL-NSTX-Res-Sep-2004

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