Stimulated wave scattering in the Smith-Purcell FEL

Frequency multiplication in the Smith-Purcell free electron laser (FEL) as a way to obtain powerful millimeter/ sub-millimeter stimulated radiation from a high-current, moderately relativistic electron beam is studied. It is shown that the main mechanism that provided the multiplication is mutual scattering of low-frequency and high-frequency waves on the electron beam. The use of this mechanism can provide the power level of tens of megawatts and the possibility of a relatively broadband (few percent) frequency tuning.