INFLUENCE OF GENERATED PUMP ELECTRIC FIELD ON MULTIHARMONIC INTERACTION OF WAVES IN AMPLIFICATION SECTION OF SUPERHETERODYNE FEL

Abstract

In the cubic nonlinear approximation, we analyze the processes of generating the electric pump field by an electron beam and its effect on the amplification of space charge waves (SCW) in the amplification section of a parametric superheterodyne free-electron laser (FEL). We found that the generated pump electric field amplitude is within 21…33% of the amplitude of the external pump electric field. We showed that the generated pump electric field is in phase with the external one. It leads to an increase in the growth increments of SCW; therefore, the length of the SCW amplification section is reduced by 22%. We found out that this field does not destroy the mode of amplification of multi-harmonic SCW. Thus, the studied effect makes it possible to create FELs with smaller longitudinal dimensions and powerful electromagnetic waves with a complex multi-harmonic spectrum.