Jm. Gong, A HIGH-EFFICIENCY FREE-ELECTRON LASER-PENIOTRON HYBRID WITH A LONGITUDINAL WIGGLER MAGNETIC-FIELD, Physics of plasmas, 4(9), 1997, pp. 3390-3393
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.