Study of RWM Stability and RWM Feedback Control in Reactor Relevant Low-Rotation Discharges in DIII-D

ORAL

Abstract

Advanced tokamak operation in ITER is expected to require active control of the resistive wall mode (RWM) [1]. After the re-orientation of 1 of 4 neutral beam injectors DIII-D is now ideally suited to address the stability of non-rotating high-beta plasmas. In discharges with balanced NBI heating the RWM becomes unstable at the no-wall stability limit. Only a modest increase of the plasma rotation is sufficient to remain stable beyond this limit suggesting a lower rotation threshold than anticipated from previous experiments, which used non-axisymmetic magnetic fields to lower the plasma rotation. Feedback experiments using an upgraded audio-amplifier system to stabilize the RWM in low-rotation plasmas have begun and comparisons with feedback modeling will be shown.\par \vskip6pt \noindent [1]~Y.\ Liu, et al., Nucl.\ Fusion {\bf 45}, 1131 (2005).

*Supported by the US DOE under DE-FG02-89ER53297, DE-AC02-76CH03073, DE-FG03-95ER54309, DE-FC02-04ER54698, and DE-FG02-03ER83657.

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Authors

  • H. Reimerdes

  • J. Bialek

  • A.M. Garofalo

    • Columbia U.

  • M.J. Lanctot

  • O. Katsuro-Hopkins

  • G.A. Navratil

    • Columbia U.

  • R. Budny

  • M. Okabayashi

  • W.M. Solomon

    • PPPL

  • M.S. Chu

    • GA

  • G.L. Jackson

  • R.J. La Haye

    • GA

  • E.J. Strait

    • General Atomics
    • GA

  • Y. In

    • Far-Tech, Inc.

  • J.S. Kim

    • FAR-TECH, Inc.