Passive and Active Stability of Kink/RWM and Rotation Control in KSTAR-relevant Equilibria

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Text of Passive and Active Stability of Kink/RWM and Rotation Control in KSTAR-relevant Equilibria

1December 1, 2009
Passive and Active Stability of Kink/RWM and Rotation Control in KSTAR-relevant Equilibria
Y.S. Park,
New York, NY, USA
December 1, 2009
Motivation
Verify suitability of the planned IVCC/passive plate design for RWM stabilization in KSTAR
Demonstrate rotation control by n=2 magnetic braking to determine an optimal rotation control strategy of KSTAR, i.e. counter-NBI vs. magnetic braking by IVCC
Possible large aspect ratio (AR) experiment under high bN of NSTX
Goals
Prerequisite : Generate KSTAR-relevant lower q95 and k, higher AR equilibria
Stability threshold of Kink/RWM with various bN, li, wall-plasma gap distance
Active stabilization of RWM
Contribution
Comparison of this XP to lower aspect ratio NSTX plasmas (possible q95 & AR effects)
Based on the NSTX-KSTAR joint experiment, support upcoming KSTAR high beta experiment by using KSTAR-relevant target equilibria
Possible support to several ITPA (MDC-2, MDC-12, MDC-4, MDC-14)
*
December 1, 2009
KSTAR High Beta Experiment is Upcoming
Major KSTAR upgrade in the year 2010 for high beta experiment
IVCC, passive plates (4 toroidal segmented IVCC n=2 field), divertor plates
First NBI & LHCD (Paux will be 3MW in 2010 and upgraded to 9.5MW until 2012)
PF power supply upgrade for double null & long pulse discharge
KSTAR achieved its goal of 2009 experimental campaign
(2009 campaign during Oct.~ Nov. 2009 - 7 weeks)
- 320kA, 3.6 sec discharge obtained (shot# 2048 on Nov. 18th 2009)
KSTAR IVCC to control plasma position &
RWM/FEC/ELM (upper/middle/lower)
December 1, 2009
Approach
Vacuum field analysis to compare the applied field spectrum of the two devices
Generate KSTAR-relevant target equilibria having following parameters (XP818)
(bN = 2.5~5.0 or higher, li = 0.6~1.0, k = 2.0, q95 and AR closest to 4.0 and 3.6, respectively)
Passive Kink/RWM stability with bN, li, gap distance change
Demonstrate n=2 magnetic braking with various input torque from NBI and applied coil current
Run plan (1 day)
Kink/RWM stability threshold
Rotation control by magnetic braking
ELM dynamics investigation