O-X mode conversion in an axisymmetric plasma at electron cyclotron frequencies

The cold plasma dielectric function is employed to represent the plasma response of an axisymmetric steady state to incident waves at frequencies on the order of the electron cyclotron frequency. A boundary layer analysis of Maxwell’s equation valid near the mode conversion region is carried out to obtain an approximate system of wave equations. The independent variables of the wave equations are the flux surface label and poloidal angle. The case is analyzed in which the O mode cut-off surface and X mode cut-off surface intersect. An integral representation of solutions is given. It is shown that for a wide class of incident waves all such waves are transmitted with total mode conversion and no mode reflection. This work cannot assure that solutions with mode reflection do not occur, although a broad search for solutions, possibly with mode reflection, was unsuccessful.