Observation of beta-induced Alfvén eigenmodes in the DIII-D tokamak

Energetic ions can drive Alfven gap modes unstable, causing large losses of fast ions. Toroidicity-induced Alfven eigenmodes (TAE) were expected to disappear into the shear Alfven continuum and become stable as the plasma beta increased. Although TAE modes may disappear, another dangerous instabilit...

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Bibliographic Details
Published in:Physical review letters 1993-08, Vol.71 (6), p.855-858
Main Authors: HEIDBRINK, W. W, STRAIT, E. J, CHU, M. S, TURNBULL, A. D
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700340 - Plasma Waves, Oscillations, & Instabilities- (1992-)
ALFVEN WAVES
BETA RATIO
CHARGED PARTICLES
CLOSED PLASMA DEVICES
CORRECTIONS
DATA
DOPPLER EFFECT
EIGENVALUES
ENERGY SPECTRA
Exact sciences and technology
EXPERIMENTAL DATA
HYDROMAGNETIC WAVES
INFORMATION
IONS
Magnetic confinement and equilibrium
NUMERICAL DATA
PARTICLE LOSSES
Physics
Physics of gases, plasmas and electric discharges
Physics of plasmas and electric discharges
PLASMA
SPECTRA
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
VELOCITY
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Summary:Energetic ions can drive Alfven gap modes unstable, causing large losses of fast ions. Toroidicity-induced Alfven eigenmodes (TAE) were expected to disappear into the shear Alfven continuum and become stable as the plasma beta increased. Although TAE modes may disappear, another dangerous instability with similar properties but approximately half the TAE frequency appears in a spectral gap that is created by finite beta effects. The measured frequency of the new mode agrees with the theoretical frequency of beta-induced Alfven eigenmodes.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.71.855