A HIGH-EFFICIENCY FREE-ELECTRON LASER-PENIOTRON HYBRID WITH A LONGITUDINAL WIGGLER MAGNETIC-FIELD

Stimulated emission from the interaction of a cold, relativistic beam of electrons gyrating in a combined solenoidal and longitudinally pola rized periodic wiggler magnetic field is considered as a source of hig h-efficiency and short-wavelength radiation. The analysis of electron motion in such a combined field shows the motion covers rich Fourier c omponents. The first Fourier component, with the cyclotron frequency o f omega(c)+k(w) upsilon(parallel to), has relatively large transverse velocity compared with die velocity of the motion. The study of the in teraction 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 transv erse plane and the evolution of the efficiency with the interaction di stance is given.