Parametric decay of upper hybrid plasma waves trapped inside density irregularities in the ionosphere

Abstract

The parametric decay of an upper hybrid (UH) wave into a lower hybrid (LH) wave and a downshifted UH wave inside inhomogeneous ionospheric striations, when both pump and decay UH modes are trapped, is investigated. The threshold and the growth rate of the instability are determined. The possibility of the existence of both main features in the usually observed spectrum of stimulated electromagnetic emission (SEE), downshifted maximum and long continuum tail, is demonstrated. The conditions of the excitation of the second and third decay modes are established.