Inhomogeneity effects on the absorption of electromagnetic high-frequency waves by magnetized Maxwellian plasmas

Abstract

Inhomogeneity effects on the absorption of high-frequency electromagnetic waves by magnetized Maxwellian plasmas are considered, and in particular the propagation and absorption of the ordinary and extraordinary modes propagating perpendicularly to the magnetic field are analysed. We show that, for small values of the ratio of the electron plasma frequency to the electron-cyclotron frequency, the inhomogeneity effects are more important for the ordinary mode, and that for values of this ratio close to or greater than unity the effects become pronounced for the extraordinary mode. It is also shown that, for a given value of this ratio, and for a fixed value of the ratio of electron-cyclotron frequency to wave frequency, the inhomogeneity effects tend to increase as the ambient magnetic field decreases. The temperature dependence of the effect, the dependence on the direction of propagation l'elative to the inhomogeneity, the influence of temperature anisotropy, and the isolated contribution of the gradients of different plasma parameters are investigated. Several circumstances in which instabilities may occur are mentioned.