Enhanced Superradiant Smith–Purcell Radiation in a Three-Mirror Quasi-Optical Cavity

Smith-Purcell (SP) radiation has been widely used for the generation of radiation from microwave to optical frequencies, and it has recently become an attractive candidate for a Terahertz (THz) radiation source. Superradiant SP radiation has sharp angular and spectral distributions due to the bunching of the electron beams, and a three-mirror quasi-optical cavity (TMQOC) which has selectivity at both angles and frequency has been designed to enhance this process. The radiation power over 700 W/m at the 99.4 GHz are obtained through using a 45-keV 4-A/m beam skip over a metal grating with period, width, and depth are 1.6, 1.0, and 0.8 mm, respectively. This results show that the TMQOC can greatly enhance the superradiant SP radiation, and one may utilize this effect to design a compact, tunable, and powerful THz radiation source working at room temperature.