Plasma waves near the double resonance layer in the ionosphere

Dispersion properties of plasma waves with frequencies close to the upper hybrid frequency _u and the multiple electron cyclotron frequency n_Be (double resonance) are considered for an inhomogeneous plasma with opposite gradients of the electron density and magnetic field magnitude. We show that a region of possible solutions of the dispersion relation decreases in real space as well as in wave vector space as of the wave frequency approaches double resonance. The results are applied to an interpretation of experiments on ionospheric modification by high-power radio waves with frequencies close to n_Be.Radiophysical Research Institute, Nizhny Novgorod, Russia. Swedish Institute of Space Physics, Uppsala Division, Sweden. Swedish Institute of Space Physics, Kiruna Division, Sweden. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 5, pp. 617–633, May, 1994.