Development of a compact cherenkov free-electron laser

A compact free-electron laser operating in the millimeter and terahertz wave range is under development. The radiation is generated via Cherenkov effect of a 50 keV electron beam passing through a waveguide loaded with silicon slabs. Comparing to the conventional undulator based FELs, our device is significantly compact because of the low energy of the electron beam. The size of the device is comparable to the THz sources fed by the solid-state fs lasers. The numerical simulation predicted an output of 2 W in average with 1 mA/50 keV CW electron beam at a frequency of 46 GHz. A test bench using the Spindt cathode as the beam source and a superconducting magnet for the beam focusing was constructed. A preliminary lasing experiment in the millimeter wave range is now under way.