Bliokh K. Interaction of waves in passive and active media

The dissertation, the main materials of which are published in 7 articles, is dedicated to the problems of interaction and propagation of waves in magnetospheres of pulsars and in systems with plasma-beam instability (PBI). It studies the following topics: the processes of linear transformation, in-duced dispersion and three-wave interaction in magnetospheres of pulsars; calculation of the influence of these processes on the ability of the radiation to leave the magnetosphere; the influence of different types of plasma inhomogeneity on the development of beam instability; large-scale inhomogeneities (WKB-approximation) and small- scale oscillator inhomogeneities. Separate treatment is given to the behavior of the waves when going through the turning point on the border of the PBI area and to the development of PBI in a periodically heterogeneous system. The problem of self-consistent interaction of waves and inhomogeneities in a bounded system with PBI (for example, UHF amplifier) is solved. It is dis covered that distributed feedback arises in such a system, and, as a consequence, the system begins to work in the automodulation mode.