Abstract
We conduct a simulation study on the acceleration of periodically loaded electrons in a 6-MeV photocathode electron gun driven by a laser beat wave with a beat frequency of 4.35 THz. The density modulation of the electrons is well preserved during particle acceleration. The periodically bunched electrons are then injected into a single-pass free-electron laser to quickly generate a few tens of kW electron superradiance at 63.5 μ.