Ginzburg-Landau equation: A nonlinear model for the radiation field of a free-electron laser

Abstract

It is shown that the nonlinear dynamics of the radiation field in a free-electron laser can be modeled by the Ginzburg-Landau equation. The refractive index of the electron beam in the nonlinear regime and the saturation intensity of the radiation field are obtained from WKB theory. Although the Ginzburg-Landau equation does not permit soliton solutions, it is shown that certain types of solitary-wave solutions have a strong resemblance to spikes observed in simulations and experiments.