Superradiant THz undulator radiation source based on a superconducting photo-injector

Superconducting radio frequency accelerators are used to produce terahertz (THz) radiation pulses with a high repetition rate. In this study, a compact high repetition rate THz radiation source has been developed based on a DC-SRF photo-injector through velocity bunching at Peking University. This compact THz source can theoretically generate approximately 1 W of superradiant THz radiation, with a repetition rate of 16.25 MHz and a frequency that can be tuned from 0.24 THz to 0.42 THz by varying the electron beam energy from 2.4 MeV to 3.1 MeV. Simulation results indicate that the asymmetrical longitudinal distribution of electrons in each bunch caused by velocity bunching increases the THz power by about 2 orders at wavelength within 400-700 μm. Experimental measurements are consistent with the calculation results when propagation loss is considered. This paper presents the system description, simulation, and experiments of the high repetition rate THz source.