Nonlinear effects in the ionosphere (cross modulation of radio waves) have been known since the 1930s. Only recently, however, has the rapid increase in the power and directivity of the radio transmitters made it possible to alter the properties of the ionosphere strongly and to modify it artificially by applying radio waves. This has revealed a variety of new physical phenomena. Their study is not only of scien tific interest but also undisputedly of practical interest, and is presently progressing very rapidly. This monograph is devoted to an exposition of the present status of theoretical research on this problem. Particular attention is paid, naturally, to problems in the development of which the author himself took part. It is my pleasant duty to thank V. L. Ginzburg, L. P. Pitaevskii, V. V. Vas'kov, E. E. Tsedilina, A. B. Shvartsburg, and Va. S. Dimant for useful discussions and for valuable remarks during various stages of the work on the problem considered in this book. Contents 1. Introduction . . . . . . . . . . . . . . . . . . .

Inhalt

1. Introduction.- 1.1 Data on the Structure of the Ionosphere.- 1.2 Features of Nonlinear Phenomena in the Ionosphere.- 2. Plasma Kinetics in an Alternating Electric Field.- 2.1. Homogeneous Alternating Field in a Plasma (Elementary Theory).- 2.2. The Kinetic Equation.- 2.3. Electron Distribution Function.- 2.4. Ion Distribution Function.- 2.5. Action of Radio Waves on the Ionosphere.- 3. Self-Action of Plane Radio Waves.- 3.1. Simplification of Initial Equations.- 3.2. Effect of Nonlinearity on the Amplitude and Phase of the Wave.- 3.3. Change of Wave Modulation.- 3.4. Generation of Harmonic Waves and Nonlinear Detection.- 3.5. Self-Action of Radio Waves in the Lower Ionosphere.- 4. Interaction of Plane Radio Waves.- 4.1. Cross Modulation.- 4.2. Interaction of Unmodulated Waves.- 4.3. Radio Wave Interaction in the Lower Ionosphere.- 5. Self-Action and Interaction of Radio Waves in an Inhomogeneous Plasma.- 5.1. Inhomogeneous Electric Field in a Plasma.- 5.2. Kinetics of Inhomogeneous Plasma.- 5.3. Modification of the F Region of the Ionosphere by Radio Waves.- 5.4. Focusing and Defocusing of Radio Wave Beams.- 6. Excitation of Ionosphere Instability.- 6.1. Self-Focusing Instability.- 6.2. Resonant Absorption and Resonance Instability.- 6.3. Parametric Instability.