Excitation of ordinary waves in a diffuse boundary plasma under an anomalous skin effect

Absorption of an electromagnetic wave by a plasma with a diffuse boundary is studied. The decrease of the particle concentration is assumed to be exponential and the magnetic field to be parallel to the plasma boundary. It is shown that collisionless absorption of waves, the electric vector of which is directed along the magnetic field, involves the excitation of ordinary waves in the plasma at those concentrations at which the waves may exist in a homogeneous plasma. The line shapes of the electron and ion absorption resonances are studied, particularly in the effective collision frequency approximation. Expressions are obtained for the limits of existence of ordinary cyclotron waves in a plasma and the dispersion equation is solved for a homogeneous high pressure plasma