EFFICIENCY ENHANCEMENT IN A CHERENKOV LASER BY A PROPER PERMITTIVITY VARIATION

With the aid of particle simulation, we discuss efficiency enhancement in a single-pass Cherenkov laser by varying the permittivity of a die lectric sheet loaded on a parallel plate waveguide. For the analysis o f the problem, a two-dimensional model for the Cherenkov laser is cons idered which is composed of a planar relativistic electron beam and a parallel plate waveguide, one plate of which is loaded with a dielectr ic sheet. In order to maintain the synchronism between an electron bea m and an electromagnetic wave, the permittivity of the dielectric is p roperly varied in accordance with the variation in the average velocit y of the electron beam. The result of numerical simulation shows that the efficiency of energy transfer from the electron beam to the electr omagnetic wave is greatly enhanced by properly varying the permittivit y of the dielectric sheet. (C) 1997 American Institute of Physics.