Self-focusing of laser beams in magnetized relativistic electron beams

Summary Form only given, as follows. Radiation focusing has been shown to play a central role in the practical utilization of the free-electron laser. The self-focusing of the laser beam in relativistic electron beams under the cyclotron autoresonance interaction has been studied by the authors. They have assumed that there is no electron density perturbation prohibited from the background magnetic field for the time scale of interest. The nonlinearity responsible for self-focusing is introduced by the energy dependence of the relativistic mass of electrons. The plasma frequency thus varies with the electron energy, which, in turn, is proportional to the radiation amplitude. The authors have examined such a relativistic nonlinear effect on the propagation of a Gaussian beam in the electron beam. A parametric study of the dependence of the laser beam width on the axial position for various electron beam densities has been performed.<>