The theory of radio windows in the ionosphere and magnetosphere—II

Abstract

A theory of radio windows in a previous paper was based on the approximations of ray theory and does not apply for a plasma in which the gradient of electron concentration is too great. Observations have shown that large gradients are often of interest and to deal with this a theory is given that uses a full wave integration of the governing differential equations. It applies only in a cold plasma. The source of the waves is a Z mode wave that arises from a plasma wave. After partial penetration of the window it gives two emergent waves, ordinary and extraordinary, whose amplitudes are calculated. The gradient of electron concentration and the effective electron collision frequency are assumed to be independent of the coordinates. At one level the refractive index for the Z mode is very large. To deal with this a standard method is used in which part of the path of integration is a contour in complex space. A possible extension to deal with still greater gradients is briefly reviewed.