Electronic Resource
[S.l.]
:
American Institute of Physics (AIP)
Physics of Plasmas
6 (1999), S. 2462-2471
ISSN:
1089-7674
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The presence of a super-thermal ion component in tokamak as well as in stellarator plasmas, can give rise to Alfvén-type instabilities. In the present paper an analytical investigation of global Alfvén eigenmodes (GAEs) in a stellarator with planar magnetic axis is performed and analytical expressions for the dominant mode numbers are derived. The effect of trapped highly energetic particles on the GAEs is investigated. The frequencies and corresponding growth rates of the discrete GAE spectrum are found for different distributions of the energetic particles. It is shown that for given background conditions, the slowing-down distributions yield the largest values for the growth rates. The inclusion of the highly energetic particles leads to a change of the conditions for the existence of GAEs and in the dominant mode numbers. A shear dependent threshold for the pressure of the trapped energetic particles has been found, above which GAEs cannot be excited. © 1999 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.873518
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