Observation and control of resistive wall modes
- General Atomics, San Diego, CA (United States)
- Columbia Univ., New York, NY (United States)
- Univ. of Texas, Austin, TX (United States); and others
Two approaches to achieving long-time scale stabilization of the ideal kink mode with a real, finite conductivity wall are considered: plasma rotation and active feedback control, DIII-D experiments have demonstrated stabilization of the resistive wall mode (RWM) by sustaining beta greater than the no-wall limit for up to 200 ms, much longer than the wall penetration time of a few ms. These plasmas are typically terminated by an m = 3, n = 1 mode as the plasma rotation slows below a few kHz. Recent temperature profile data shows an ideal MHD mode structure, as expected for the resistive wall mode at beta above the no-wall limit. The critical rotation rate for stabilization is in qualitative agreement with recent theories for dissipative stabilization in the absence of magnetic islands. However, drag by small-amplitude RWMs or damping of stable RWMs may contribute to an observed slowing of rotation at high beta, rendering rotational stabilization more difficult. An initial open-loop active control experiment, using non-axisymmetric external coils and a new array of saddle loop detectors, has yielded encouraging results, delaying the onset of the RWM.
- Research Organization:
- General Atomics, San Diego, CA (United States); Princeton Univ., Princeton Plasma Physics Lab., NJ (United States); Oak Ridge National Lab., TN (United States); Lawrence Livermore National Lab., CA (United States); Univ. of Texas, Austin, TX (United States); Columbia Univ., New York, NY (United States); Univ. of Wisconsin, Madison, WI (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC03-89ER51114; AC02-76CH03073; AC05-96OR22464; W-7405-ENG-48
- OSTI ID:
- 296840
- Report Number(s):
- GA--A22994; CONF-981064--; ON: DE99001355
- Country of Publication:
- United States
- Language:
- English
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