Table of contents

The review is based in 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.

Population synthesis is a method for numerical simulation of the population of objects with a complex evolution. This method is widely used in astrophysics. We consider its main applications to studying astronomical objects. Examples of modeling evolution are given for populations of close binaries and isolated neutron stars. The application of the method to studying active galactic nuclei and the integral spectral characteristics of galaxies is briefly discussed. An extensive bibliography on all the topics covered is provided.

Processes of vortex generation in a weakly ionized gas are reviewed in circumstances where a high-speed flow propagates along the gas discharge and acoustic waves interact with a positive column. Results on the effect of longitudinal gas flow in the positive-column properties are presented. It is shown that in certain conditions the gas flow in the positive column gives rise to vortices that cause the plasma to mix radially, producing a uniformly excited gas at high pressures. Results concerning the interaction of acoustic waves with low-temperature plasma are reviewed, and the acoustic-stimulated formation of vortex motion leading to an uncontracted discharge at elevated pressures is discussed. Also examined are flashes of superluminescence in an argon discharge caused by an abrupt transition of a positive column containing acoustic vortices from the uncontracted state to the contracted one at heightened pressures; this transition is understood to occur because of the turbulent-to-laminar transition in the acoustic flow. Finally, a gas-discharge acoustically induced laser is described.

Studies of the electron instability effects (EIEs) in structures based in strongly correlated electron systems (SCESs), such as high-temperature superconductors (HTSCs) and doped manganites (compounds with colossal magnetoresistance), are reviewed. These effects manifest themselves in a change of several orders of magnitude in the resistive state of the normal metal–HTSC or normal metal–DM (doped manganite) interface in an electric field under significant current injection conditions. The results of studying HTSC- and doped-manganite-based heterojunctions are considered. EIEs in heterostructures are compared with the electric field effect on the properties of an SCES in thin fllms and gate-containing devices. The general features and distinctions in the physics of these ðhenomena are analyzed.

A brief review is given of the 1952 –1988 research at the A I Leipunsky Institute of Physics and Power Engineering (Obninsk) on the use of nuclear fission chain reactions in developing space vehicles and their on-board power systems. The research was carried out in the initiative of the USSR Acadamy of Sciences Corresponding Member DI Blokhintsev, Head of the Institute, and enlisted the active support of Academician S P Korolev.