The dynamics of a broad spectrum of oscillations in scattering of electromagnetic waves by a relativistic beam

The nonlinear theory of scattering of multimode electromagnetic oscillations by a relativistic electron beam is examined. The principal stabilization mechanism for the instability that arises under anomalous Doppler effect is based on the following two effects: the beam retardation and the relativistic dependence of the plasma oscillations frequency of the beam on the amplitude. In the case of monochromatic pumping, the spectrum of the scattered wave is shown to broaden as the relativistic character of the beam grows. With a nonmonochromatic pumping, an effective excitation of the monochromatic signal wave takes place, with a process efficiency reaching 50-60%.