Nonlinear dynamics in a free electron laser amplifier with electromagnetic pumping

Summary form only given. In this paper, we discuss nonlinear dynamics of a model of a scattron FEL amplifier based on the induced backscattering of two transversal electromagnetic waves on a relativistic electron beam. We consider the electromagnetic waves to be fast waves with group velocities equal to the speed of light. We investigate the dynamics of the system in the case of a moderately relativistic electron beam. Numerical simulations show that in the system self-modulation takes place. The self-modulation effect in FEL-amplifier was observed for the first time in. Apart from our approach correctly considers the frequency dependence of the FEL gain. The physical origin of self-modulation in the FEL amplifier is the parasitic feedback that takes place due to counter propagation of the pump wave.