A.V. Gurevich Lebedev Physical Institute, Russian Academy of Sciences, Leninsky prosp. 53, Moscow, 119991, Russian Federation
This review is based on the report under the same title presented at the joint scientific session of the Physical Sciences Division, RAS and the Scientific Council of P N Lebedev Physical Institute celebrating the 90th birthday of Academician V L Ginzburg, October 4, 2006 [see Phys. Usp.50 (5) 529 (2007)]. (Note by the Editorial Board.)
The review is based on a report presented by the author at the RAS Physical Sciences Division’s session in honor of Vitaly L Ginzburg’s 90th birthday. It examines the current status of theoretical and experimental research on nonlinear phenomena arising when a powerful radio wave propagates in the ionosphere. The focus is on the modification of the ionosphere under the resonance excitation of natural plasma oscillations by radio waves. The upper-hybrid resonance gives rise to strong upper- and lower-hybrid plasma waves; excites strongly elongated ionospheric irregularities, and induces artificial ionospheric radio emission. Nonlinear processes are found to undergo complete transformation near double resonances, when the upper-hybrid frequency is close to a multiple of the electron gyromagnetic frequency. In the neighborhood of the Langmuir resonance, intense plasma waves and ion-sound waves are excited, electrons are effectively accelerated, and an artificial glow of the ionosphere appears.