The Green' function forwaves in a homogeneous anisotropic absorbing plasma

Abstract

The Green's function (or matrix) for a source of sinusoidal time dependence in an infinite homogeneous absorbing magneto-ionic plasma is written as a Fourier integral over wavenumber space. It is shown that this Fourier integral solution exists, and is unique as a generalized function. By extending the Fourier integral to complex wavenumbers, it is shown that the far-field expression for the Green's function may be written as an integral over sections of the dispersion surface, which in this case is a complex sub-manifold of the space of three complex variables. Use of the saddle-point method in two dimensions allows a further simplification of the far-field result. The matrix coefficients in the resulting expression are shown to represent a decomposition into modes. Corresponding results are also obtained for sources with spatial dependence, described by either functions of compact support or rapidly decreasing functions.