Type-I ELM Suppression by Resonant Fields in Steady State Hybrid Plasmas on DIII-D
ORAL
Abstract
``Steady-state'' hybrid plasmas in DIII-D with zero surface loop voltage have been maintained for $\le$2 current relaxation times with complete suppression of Type-I ELMs using n=3 Resonant Magnetic Perturbations (RMPs). The edge $q_{95} \approx$ 6 and q(0) $>$1 due to anomalous poloidal magnetic flux pumping in the hybrid scenario. The sustained hybrid performance without type-I ELMs indicates an alternative mechanism for flux pumping, possibly due to the interaction of the m/n=3/2 mode with an m=1/n=1 kink displacement. The plasma confinement degradation during ELM suppression is less than 10$\%$, with H$_{98y2} \approx$ 1.2 sustained for the duration of the discharge. After ELM suppression is obtained, $\sim$1 kHz D-alpha bursts are observed. The underlying instability may be beneficial for particle and impurity control.
*Work supported by the US DOE under DE-AC02-09CH11466, DE-FC02-04ER54698, DE-FG02-04ER54761, DEFG02-08ER54984 and DE-FG02-89ER53296.
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