A FREE ELECTRON LASER WITH ELECTROMAGNETIC PUMPING WAVE
电磁波泵浦的自由电子激光器

A free electron laser with electromagnetic pumping wave is studied. A drifting and rotating electron ring with large radius comes from a magnetic cusp, goes through a cylindrical waveguide and interacts with TEn modes of the waveguide. By making use of the Vlasov distribution theory and the three dimensional wave equation of waveguide modes, the dispersion relation of scattered waves in Compton region is deduced. According to the numerical analysis, the growth rate and frequency of scattered wave as a function of guide mag netic field, electron beam energy, electron cvclotron ratio and radial position of electron ring have been discussed.