Modulation of an intense beam by an external microwave source in the non-linear regime — theory and simulation

A time dependent, fully electromagnetic particle code is used to simulate the current modulation in an intense relativistic electron beam (IREB) by an external rf source in the nonlinear regime. It is shown that non-linear effects, responsible for the high modulation levels seen in the experiments(1,2), may be explained via simple models and the non-linear propagation of fast and slow space charge waves. Qualitative and quantitative agreement between the theory and simulations is obtained.