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Assessment of Performance of Dynamic Error Field Correction Near-magnetic-axis against Residual Error Field Using Fishbone-driven RFA M. Okabayashi NSTX Macro Stability Breakout Session 2009_12_01.
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Assessment of Performance of Dynamic Error Field Correction Near-magnetic-axis against Residual Error Field Using Fishbone-driven RFAM. OkabayashiNSTX Macro Stability Breakout Session2009_12_01
Assessment of performance of Dynamic Error Field Correction near-magnetic-axis against residual error field using fishbone-driven RFA • • q=1fisbone triggers a finite amplitude of n=1 RFA • near the magnetic axis due to residual error field • • DEFC is one of the best tools for minimizing the impact by residual error field. • • Probably, ITER needs the capability of DEFC near magnetic axis • • A question: Does DEFC work even near the axis without negative impacts at other radii?
Strong coupling was observed between the q=1 fishbone and n=1 RFA due to residual error field (DIIID)
n=1 RFA amplitude (originated as external kink RWM) increases with q=1 internal kink fishbone (DIIID)
The strong impact of n=1 RFA amplitude on the rotation near the axis (rho~ 0.4) implies that the RFA has finite internal component (DIIID).
Proposed experiment- the n=1 feedback (DEFC) against fishbone-driven RFA due to residual error field • Assess the DEFC performance near the axis for ITER with fishbone-driven RFA. - no impact on other area? - how effective? • Plasma condition: - q=1 fishbone onset condition - low rotation near the axis