Design of large orbit gyrotron electron beam double- cusp gun

Theoretical model of a double- cusp gun for Ka- band second harmonic gyro- TWT amplifier was analyzed, and the electron beam performance parameters were calculated. Using EGUN simulation, a double- cusp gun producing large orbit gyration electron beam was designed with an anode voltage of 70 kV and a beam current of 3.35 A. The ratio of perpendicular to parallel velocity was 1.62 and its velocity spread was 4.2%. The distribution of electron beam velocity ratio and velocity spread on axis was discussed, and the effects of the anode voltage on electron beam performance was studied. The reseults show that proper anode voltage and cathode magnetic field are helpful in getting good electron beam parameters.