Theory of heating in the lower ionosphere by obliquely incident waves from a powerful point transmitter

Abstract

In the study of wave interaction it is necessary to know the power absorbed per unit volume of the anisotropic ionospheric plasma, from the disturbing radio wave radiated by a powerful point transmitter. This depends on height, range and direction. The problem is first considered when there are only two obliquely upgoing waves. The two magnetoionic components that reach the same real point in the ionosphere are incident at different complex angles. They are added, with allowance for their relative phase, to give an interference pattern in three dimensions. The time average of the power absorbed per unit volume is found from the total electric intensity and the resulting current density. It is equal to minus the divergence of the time averaged Poynting vector. To study these effects and to illustrate the methods of calculation, a semi-infinite homogeneous cold electron plasma with a sharp lower boundary is used as a model of the ionosphere. Calculation for points in the magnetic meridian plane is simplest and is explained first. It is then shown that for other directions a similar method can be used by rotating the coordinate axes about the vertical through a suitable complex angle. The effect of including two further waves, that have been reflected at a higher level, is also studied. Some typical results are presented.