Above plasma frequency radiation at intense beam-plasma interaction

For the case of large angle scattering beam the mechanism of plasma FEL brings to the spectrum broadening during beam-plasma interaction. This mechanism is mostly effective for the high-current beam because intensity of radiation is proportional to the squared density of the beam particles. If REB is not moment scattered then the beam-plasma instability itself leads to the excitation of broadband oscillation spectrum. For such values of the nonlinear dynamics the instability is chaotic. Excited oscillations are nonregular and have continuous spectrum. It should be noted that fast thermalization not only of plasma particles but the particles of the initially monoenergetic beam takes place. The above plasma frequency FEL-mechanism can make its contribution to the broadband spectrum excitation.