PARAMETRIC DECAY OF AN ELECTRON-BERNSTEIN WAVE EXCITED BY THE OPTICAL MIXING OF 2 MICROWAVE BEAMS

Nonlinear theory of an electron-Bernstein wave at lower-hybrid frequency is developed. Fluid theory is applied for the excitation of a lower-hybrid wave whereas a kinetic model is used for the electron-Bernstein mode as fluid theory breaks down for short-wavelength perturbations, and the propagation of these waves depends upon the cyclotron motion of the electrons about the field fines. The nonlinearity arises because of electrons motion, introduced through ponderomotive force. The electron-Bernstein wave is assumed to be excited by optical mixing of two microwave beams. The nonlinear dispersion relation and growth rates are calculated for three-wave and four-wave parametric interaction processes. Since the electron-Bernstein wave is nonlinearly excited by two intense beams, there is no power threshold and the excited power increases proportionally to the product of the incident powers. The investigation appears to be of great potential because of recent significant developments in gyrotron technology.