Fast particle finite orbit width and Larmor radius effects on low-{ital n} toroidicity induced Alfv{acute e}n eigenmode excitation
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 (United States)
The effects of finite drift orbit width (FOW) and Larmor radius (FLR) of fast particles on the stability of low-{ital n} toroidicity-induced Alfv{acute e}n eigenmodes (TAE) are studied. The formulation is based on the solution of the low frequency gyrokinetic equation ({omega}{lt}{omega}{sub c}, where {omega}{sub c} is particle cyclotron frequency). A quadratic form has been derived in terms of invariant variables; energy E, magnetic moment {mu}, and toroidal angular momentum P{sub {var_phi}}. The growth rate of the TAE is computed perturbatively using numerical averaging over the fast particle drift orbit. This new computational capability improves the NOVA-K code [G. Y. Fu, C. Z. Cheng, and K. L. Wong, Phys. Fluids B {bold 5}, 4040 (1994)] which included FOW effects in the growth rate calculation based on small radial orbit width approximation. The new NOVA-K version has been benchmarked for different regimes of particle TAE excitation. It is shown that both FOW and FLR effects are typically stabilizing; the TAE growth rate can be reduced by as much as a factor of 2 for tokamak fusion test reactor supershots [D. J. Grove and D. M. Meade, Nucl. Fusion {bold 25}, 1167 (1985)]. However, FOW may be destabilizing for the global modes, which are localized at the plasma edge. {copyright} {ital 1999 American Institute of Physics.}
- OSTI ID:
- 349356
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 7 Vol. 6; ISSN 1070-664X; ISSN PHPAEN
- Country of Publication:
- United States
- Language:
- English
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