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.

Authors

  • Raffi Nazikian

    • PPPL
    • Princeton Plasma Physics Laboratory
  • B.A. Grierson

    • PPPL
  • E. Kolemen

    • PPPL
  • Xi Chen

    • GA
  • C. Paz-Soldan

    • GA
  • C.C. Petty

    • GA
  • M.A. Van Zeeland

    • GA
  • F. Turco

    • Columbia U.
  • T.L. Rhodes

    • UCLA
  • G.R. McKee

    • U. Wisconsin