Nonstationary parametric processing in a semibounded plasma

Summary form only given, as follows. We consider the interaction of two transverse waves and one longitudinal surface wave in a relativistic electron beam plasma system with a sharp boundary. The space-time evolution of this three wave interaction process leads to a diffusion broadening in space of the electromagnetic wave packets. The diffusion length is determined. These investigations are very important for plasma electronics and free-electron lasers because the nonlinear wave interaction processes may lead to up conversion of the frequency of the scattered wave as compared to the frequency of the incident electromagnetic wave.