Fine-structure of electromagnetic radiation reflected from the O–X mode conversion zone in magnetized plasma

Abstract

The linear coupling between the ordinary and extraordinary waves in the vicinity of the plasma cutoff is used for the heating of overdense plasma in toroidal magnetic devices. If the mode coupling is not perfect, there is reflected ordinary wave radiation. In this paper, we analyze the structure of this radiation in a realistic case of an incident beam with a finite aperture. It is shown that reflection from the evanescent layer in inhomogeneous gyrotropic plasma results in wave distributions with a non-zero-angular momentum. A helicity of the reflected beam results in unusual effects, at least in the plasma electrodynamics, which are identified and discussed.