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Gyrokinetic theory of perpendicular cyclotron resonance in a nonuniformly magnetized plasma

Journal Article · · Phys Fluids B; (United States)
DOI:https://doi.org/10.1063/1.858935· OSTI ID:5961296
The extension of gyrokinetic theory to arbitrary frequencies by Chen and Tsai (Phys. Fluids /bold 26/, 141 (1983); Plasma Phys. /bold 25/, 349 (1983)) is used to study cyclotron absorption in a straight magnetic field with a perpendicular, linear gradient in strength. The analysis includes the effects of magnetic field variation across the Larmor orbit and is restricted to propagation perpendicular to the field. It yields the following results for propagation into the field gradient. The standard optical depths for the fundamental O-mode and second harmonic X-mode resonances are obtained from the absorption profiles given in this paper, without invoking relativistic mass variation (see also Antonsen and Manheimer, Phys. Fluids /bold 21/, 2295 (1978)). The compressional Alfven wave is shown to undergo perpendicular cyclotron damping at the fundamental minority resonance in a two-ion species plasma and at second harmonic resonance in a single-ion species plasma. Ion Bernstein waves propagating into the second harmonic resonance are no longer unattenuated, but are increasingly damped as they approach the resonance. It is shown how the kinetic power flow affects absorption profiles, yielding information previously obtainable only from full-wave theory. In all cases, the perpendicular cyclotron damping arises from the inclusion of magnetic field variation across the Larmor orbit.
Research Organization:
Culham Laboratory, Abingdon, Oxfordshire, OX14 3DB, England (Euratom/UKAEA Fusion Association)(GB)
OSTI ID:
5961296
Journal Information:
Phys Fluids B; (United States), Journal Name: Phys Fluids B; (United States) Vol. 1:8; ISSN PFBPE
Country of Publication:
United States
Language:
English