Enhancement of Smith—Purcell radiation with surface-plasmon excitation

With the aid of a three-dimensional particle-in-cell code simulation, the enhancement of Smith—Purcell radiation with a surface-plasmon mode excited by a single electron bunch and by a premodulated electron beam is considered in the paper. In the simulation, the model is a grating covered by Ag film. The results demonstrate that when the surface-plasmon mode is excited by a single electron bunch, the maximum radiation occurs at an observation angle depending on the surface-plasmon frequency, and the radiation power can be enhanced more than ten times. And for pre-bunched electron beam excitation, when one of the harmonics of the bunching frequency is resonant with that of the surface-plasmon mode, the radiation power is twenty times more than that from a perfectly conducting grating excited by the same premodulated electron beam