EMW Transformation in Weakly Nonlinear Plasma When Transverse DC Magnetic Field is Suddenly Switched off

Abstract

Linear transformation of plane, monochromatic electromagnetic wave (EMW) in plasma when external static magnetic field is suddenly switched off is considered, in radio approximation, in longitudinal propagation and transverse propagation. The same problem in weakly nonlinear plasma (longitudinal propagation) is considered. In linear theory it was shown, in both cases of propagation, that when angular frequency of source wave had specific values, most of the energy of the source wave was converted to the energy of new created wiggler magnetic field in isotropic plasma medium. Wiggler magnetic field has application for generation of coherent radiation in Free Electron Laser. In the case of transverse propagation it was shown that EMW of an elliptic polarization was transformed in transverse wave modes. The existence of an electric field component in direction of propagation couses perturbation of the electron plasma density. Transformation of the source wave in weakly nonlinear plasma was analyzed by the perturbation theory of the second order, in radio approximation.