Stimulated scattering of a plasma wave on a relativistic electron beam

The theory of collective processes at stimulated coherent scattering of a plasma wave impinging an electron beam is developed. A system of non-linear equations describing variations of field amplitudes of interacting waves and electron beam motion, which is assumed to be relativistic in the general case, is obtained. Cases of electron beam scattering by accompanying and counter-running plasma waves are considered, and elementary mechanisms inherent in this scattering are clarified. Anomalous scattering in combination with parametric Cherenkov radiation represent these mechanisms in case of electron beam scattering on an accompanied plasma wave, while at scattering on a counter-running plasma wave - normal scattering in combination with parametric Cherenkov radiation. Increments of scattering process increase both in case of nonrelativistic and relativistic beams are determined, and contributions of elementary processes to the values of increments are clarified. Possible mechanisms of saturation of scattering processes are considered