Conversion between cold plasma modes in an inhomogeneous plasma

Abstract

For a particular angle of incidence, it is possible for an ordinary mode electromagnetic wave, incident on an inhomogeneous plasma slab, to be totally converted into an extraordinary mode. A previous analysis of this process has been extended to permit an arbitrary angle of incidence and to include magnetic field gradients. Although this process has recently been proposed as a method by which toroidal plasmas might be electron cyclotron heated from the outside (low magnetic field region), it was found that for plasma parameters characteristic of modern tokamaks, significant mode conversion occurs only for waves incident within a very narrow cone (δϑ∼1°) about the critical angle. Also addressed is the question of the location at which ordinary/extraordinary mode conversion occurs.