Enhancement of terahertz Smith–Purcell radiation by two electron beams

An approach to the enhancement of terahertz (THz) Smith–Purcell (SP) radiation from an open rectangular grating driven by two electron beams is presented in this paper. In the present work, two electron beams with a velocity separation propagating over the grating are employed. With the help of a two-dimensional particle-in-cell simulation, some nonlinear processes from spontaneous emission to superradiant radiation are demonstrated. The simulation results show that the enhancements of SP radiation power, the shortened saturation time, and the lower threshold current can be obtained at an optimum voltage ratio due to the two-beam interaction.