Feedback stabilization of an l = 0, 1, 2 high-beta stellarator
Feedback stabilization of the Scyllac 120/sup 0/ toroidal sector is reported. The confinement time was increased by 10-20 ..mu..s using feedback to a maximum time of 35-45 ..mu..s, which is over 10 growth times of the long-wavelength m = 1 instability. These results were obtained after circuits providing flexible waveforms were used to drive auxiliary equilibrium windings. The resultant improved equilibrium agrees well with recent theory. It was observed that normally stable short-wavelength m = 1 modes could be driven unstable by feedback. This instability, caused by local feedback control, increases the feedback system energy consumption. An instability involving direct coupling of the feedback l = 2 field to the plasma l = 1 motion was also observed. The plasma parameters were: temperature, T/sub e/ approximately equal to T/sub 1/ approximately equal to 100 eV; density, n/sub e/ approximately equal to 2 x 10/sup 16/ cm/sup -8/; radius, a approximately equal to 1 cm; and ..beta.. approximately equal to 0.7. Beta decreased significantly in 40 ..mu..s, which can be accounted for by classical resistivity and particle loss from the sector ends.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6731926
- Report Number(s):
- LA-7243; TRN: 78-015417
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PLASMA MACROINSTABILITIES
STABILIZATION
SCYLLAC DEVICES
STELLARATORS
FEEDBACK
HIGH-BETA PLASMA
TOROIDAL CONFIGURATION
ANNULAR SPACE
CLOSED PLASMA DEVICES
CONFIGURATION
INSTABILITY
PINCH DEVICES
PLASMA
PLASMA INSTABILITY
THERMONUCLEAR DEVICES
TOROIDAL PINCH DEVICES
TOROIDAL THETA PINCH DEVICES
700107* - Fusion Energy- Plasma Research- Instabilities