A high-efficiency free-electron laser-peniotron hybrid with a longitudinal wiggler magnetic field

Abstract

Stimulated emission from the interaction of a cold, relativistic beam of electrons gyrating in a combined solenoidal and longitudinally polarized periodic wiggler magnetic field is considered as a source of high-efficiency and short-wavelength radiation. The analysis of electron motion in such a combined field shows the motion covers rich Fourier components. The first Fourier component, with the cyclotron frequency of ωc+kwv∥, has relatively large transverse velocity compared with the velocity of the motion. The study of the interaction of this Fourier component with the peniotron electromagnetic mode indicates that a high efficiency of 36% is obtained. Its working mechanism is explained and the influence of the wiggler field on the saturation efficiency is analyzed. The electron bunching in the transverse plane and the evolution of the efficiency with the interaction distance is given.