Remote feedback stabilization of tokamak instabilities

Journal Article · Sun May 01 00:00:00 EDT 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870698· OSTI ID:5006912

Sen, A K ^[1]

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1. Plasma Physics Laboratory, Columbia University, New York, New York 10027 (United States)

A novel remote suppressor consisting of an injected ion beam has been used for the stabilization of plasma instabilities. A collisionless curvature-driven trapped-particle instability, an [bold E][times][bold B] flute mode and an ion temperature gradient (ITG) instability have been successfully suppressed down to noise levels using this scheme. Furthermore, the first experimental demonstration of a multimode feedback stabilization with a single sensor--suppressor pair has been achieved. Two modes (an [bold E][times][bold B] flute and an ITG mode) were simultaneously stabilized with a simple state-feedback-type method where more state'' information was generated from a single-sensor Langmuir probe by appropriate signal processing. The above experiments may be considered as paradigms for controlling several important tokamak instabilities. First, feedback suppression of edge fluctuations in a tokamak with a suitable form of insulated segmented poloidal limiter sections used as Langmuir-probe-like suppressors is proposed. Other feedback control schemes are proposed for the suppression of electrostatic core fluctuations via appropriately phased ion density input from a modulated neutral beam. Most importantly, a scheme to control major disruptions in tokamaks via feedback suppression of kink (and possibly) tearing modes is discussed. This may be accomplished by using a modulated neutral beam suppressor in a feedback loop, which will supply a momentum input of appropriate phase and amplitude. Simple theoretical models predict modest levels of beam energy, current, and power.

• DOE Contract Number: FG02-87ER53257
• OSTI ID: 5006912
• Journal Information: Physics of Plasmas; (United States), Vol. 1:5; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
TOKAMAK DEVICES
PLASMA INSTABILITY
FEEDBACK
FLUTE INSTABILITY
ION TEMPERATURE
KINK INSTABILITY
LANGMUIR PROBE
TEARING INSTABILITY
TRAPPED-PARTICLE INSTABILITY
CLOSED PLASMA DEVICES
ELECTRIC PROBES
INSTABILITY
PLASMA MACROINSTABILITIES
PROBES
THERMONUCLEAR DEVICES
700340* - Plasma Waves
Oscillations
& Instabilities- (1992-)
700310 - Plasma Confinement- (1992-)