On excitaion of slow transverse magnetic waves for plasma heating in the low hybrid frequency range

A linear problem of excitation of slow waves in a plasma is considered. The antenna system includes a set of waveguides opening at the level of a wall confining the plasma. The waveguides are oriented in such a manner as to excite an E wave having a singularity near the lower hybrid resonance. The boundary conditions on the plasma surface have been defined with due account for wave propagation in the inhomogeneous plasma of the peripheral region. Reflection factors and plasma absorption spectra depending on the size and number of waveguides, plasma parameters and chamber wall impedance have been obtained. It is shown that the spectrum of waves penetrating into inner layers of the plasma is achieved with a great number of radiating waveguides, irrespective of the wall impedance. The optimum spectrum can also be achieved with only two waveguides provided proper corrugation of metal walls of the chamber