A slow wave free-electron laser

A simple calculation of a free-electron laser in the Compton regime that uses a dielectric-lined waveguide is presented. The introduction of a dielectric lining in a free-electron laser considerably reduces the requirements on beam voltage for generating a given frequency omega /sub 1/=k/sub 0/c/(1 - v/sub b/ eta /c), where k/sub 0/ is the wiggler wave period eta is the effective index of refraction (1< eta < square root epsilon ) and epsilon is the permittivity. The system supports electromagnetic waves whose Poynting flux is largely concentrated in the dielectric; hence the electron beam is required to propagate close to the dielectric lining. The mode structure and dispersion behavior of the guiding system without the beam are discussed. a thin annular beam is introduced, and a perturbation theory is used to obtain the frequency and growth rate of radiation.<
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