A rigorous formalism for the computation of the impedance of finite-length ICRH antennae is derived i n which proper care is taken of a correct description of the antenna ends. The results are compared with those obtained from previous infinite-length calculations. The ensuing modification of the wave spectrum imposed on the plasma and the antenna end effects lead to important changes with respect to the earlier results. In particular, a substantial decrease of coupling to the plasma is predicted for short and wide antenna designs.
Conceptual study of an ICRH traveling-wave antenna system for low-coupling conditions as expected in DEMO