The Smith-Purcell Radiation in the Grating-well Structure

The emergence of the fine micro-nano structure has advanced the development of traditional radiation. The periodical micro-nano structure can not only regulate the electromagnetic wave, but also have the potential to improve the intensity and directionality of radiation from moving electrons. We introduce the diaphragms in the grating structure to control the Smith-Purcell radiation intensity and directionality. Smith-Purcell can be seen as the radiation from the surface current, which is induced by the moving electrons. The simulation with the theory analysis shows that the diaphragms can not only enhance the intensity of the surface current, but also adjust the distribution of it. The changes of the radiation from the fine micro-nano structure demonstrated a more powerful way to control the radiation, and it is of significance in developing electron beam driven THz radiation source.