High-beta stability of tokamaks with energetic particles
The theory investigated the situation in which an anisotropic population of hot particles (ions or electrons, beam injected or rf heated) is mirror trapped on the unfavorable-curvature side of a standard tokamak. The magnetic drift frequency of these particles is assumed to be much larger than the typical interchange growth rate, but not drift reversed. In this limit, the linear stability of high-mode-number ideal magnetohydrodynamic ballooning modes can be obtained by numerical solution of an integro-differential equation that is derived from a lower bound to the low-frequency kinetic variational principle. For simplicity, a large-aspect-ratio, shifted-circle model equilibrium was adopted, in which the plasma beta is small but has a finite gradient localized in a thin radial layer. Although this analysis underestimates stability, the results still indicate that energetic particles trapped can stabilize ballooning modes for all ..cap alpha../sub c/ and shear values up to S = 0.9.
- OSTI ID:
- 5398915
- Journal Information:
- IFS Newsl.; (United States), Vol. 3:1
- Country of Publication:
- United States
- Language:
- English
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