Penetration of high-frequency waves into a weakly inhomogeneous magnetized plasma at oblique incidence and their transformation to Bernstein modes

Abstract

Propagation of high-frequency electromagnetic waves in a weakly inhomogeneous magnetized plasma is investigated. We suppose the density gradient to be perpendicular to an external magnetic field, and the waves to be incident obliquely upon the plasma from vacuum. We find that the transmission coefficient of the ordinary wave through the plasma resonance is approximately equal to one in a fairly wide range of angles of incidence γ near the value γ0 = arcsin (Ωc/)(Ωo + Ω) ½. The transmitted ordinary wave is fully transformed into an extraordinary wave at higher densities. Then it propagates back to the region of a smaller density, and is fully transformed into the Bernstein modes in the vicinity of the hybrid resonance. Complications connected with the evanescent layer, which arise when the high-frequency energy is transmitted into the plasma in the form of the extraordinary wave, can thus be removed by using the ordinary wave with the angle of incidence chosen appropriately.