Induced scattering of plasma waves by a relativistic electron beam

The general case of induced coherent scattering of plasma waves by a relativistic electron beam is considered for noncollinear wave vectors of interacting waves, specifically, the plasma pump wave, the scattered electromagnetic wave, and the high-frequency space-charge wave produced by the combined action of incident and scattered waves. In terms of the three-wave interaction model, the general nonlinear dispersion relation describing the initial stage of the induced scattering is obtained. Both the Raman and Compton mechanisms of scattering are considered. The corresponding amplification factors and the dependence of these factors on the angular characteristics are obtained. The frequencies of the scattered electromagnetic waves are determined. The possibility of using plasma waves as effective undulators is discussed in relation to the free-electron laser realization for obtaining short wave radiation by using moderately relativistic electron beams. 6 refs