Oblique propagation of electromagnetic waves in a kappa-Maxwellian plasma
- Vakgroep Toegepaste Fysica, Universiteit Gent, Jozef Plateaustraat 22, B-9000 Gent (Belgium)
Space plasmas are often observed to contain more particles in the high-energy tail than the usual Maxwellian distributions, and are well modeled by kappa distributions. The hybrid kappa-Maxwellian distribution and associated generalized plasma dispersion function Z{sub {kappa}}{sub M} were recently introduced to model magnetized space plasmas. The susceptibility tensor for a kappa-Maxwellian plasma component is derived, making use of Z{sub {kappa}}{sub M}. This enables one to make general studies of obliquely propagating electromagnetic waves in a magnetoplasma. The susceptibility and dielectric tensors reduce to the Maxwellian expressions in the limit {kappa}{yields}{infinity}. As an illustration, the formalism is applied to the lower branch of the R mode and its off-parallel variant. For low {kappa} values, low-wavenumber, low-frequency parallel whistler waves are shown to be stable, unlike the Maxwellian case, which is unstable if the perpendicular temperature exceeds the parallel temperature. A numerical study is made of the effects of the value of kappa, the propagation angle, and the temperature anisotropy ratio on dispersion and damping. The kappa-Maxwellian distribution with very low {kappa} is found to be unstable in an overdense plasma near the electron-cyclotron frequency even when the parallel and perpendicular temperatures are equal, because of the anisotropy of the contours in velocity space.
- OSTI ID:
- 21072618
- Journal Information:
- Physics of Plasmas, Vol. 14, Issue 8; Other Information: DOI: 10.1063/1.2766647; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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