THREE-DIMENSIONAL ANALYSIS OF ELECTROMAGNETICALLY PUMPED FREE-ELECTRON-LASER

An analysis of the electromagnetieally pumped free-electron-laser, which includes a solid relativistic electron beam and a cylindrical waveguide, is presented in this paper. Linear and nonlinear dispersion relations are derived. The mode structure is investigated and the instability growth rates are formulated for both the Raman regime and high-gain Compton regime. The results show that the growth rates closely depend on the amplitude and fre-quency of the pump wave, the electron density, and the electron energy. The growth rates are also related to the radii of the electron beam and waveguide, as well as the structure of coupled modes. The growth rates can be greatly enhanced as long as reasonable parameters are chosen. In addition, a comparison of theoretical and experimental results is finally given in the present paper.