Design studies on a 500kV DC gun photo-injector for the BXERL test facility

BXERL is a proposal for a test facility(Beijing X-ray Energy Recovery Linac),which requires its injector to provide an electron beam of 5 MeV,77 pC/bunch at a repetition rate of 130 MHz(average current of 10 mA).In this paper,we present the design of the injector,which consists of a 500 kV photocathode DC gun equipped with a GaAs cathode preparation device,a 1.3 GHz normal conducting RF buncher,two solenoids,and one cryomodule containing two 1.3 GHz 2-cell superconducting RF cavities as the energy booster.The detailed beam dynamics show that the injector can generate electron bunches with a RMS normalized emittance of 1.49 πmm·mrad,a bunch length of 0.67 mm,a beam energy of 5 MeV and an energy spread of 0.72%.