Coupler impedance calculations for ICRF heating of large tokamaks

A simple two-dimensional model for evaluating the efficiency of ICRF coupling to a slab plasma is developed. The model takes advantage of the very low plasma surface impedance associated with the propagating magnetosonic wave to obtain lowest order analytical expressions for the surface RF magnetic field. The calculations are used to compare the loading characteristics of a simple loop antenna with a cavity resonator for high power ICRF heating.