Low-voltage hybrid FEL with comb waveguide

The research results of hybrid free-electron laser (FEL) design consisting of resonator and magnetron gun are presented here. The resonator is made of a circular waveguide segment and the periodic structure, which has form hollow cylindrical waveguide with transversal slits, is placed in this segment. When accelerating voltage was up to 20 kV the device radiated microwave power in 2-3 cm wavelength range. It was established that radiation was caused by synchronism of longitudinal velocity of cyclotron electron beam motion with phase velocity of slow space harmonic of the tube periodic structure. The synchronism of the wave and electron beam took place in a wide range of accelerating voltages. Cyclotron beam motions were driven by the leading magnetic field of the electrical magnet.