Simulation calculation for Ka-band second-harmonic Gyro-TWT Using a helical corrugation waveguide

The eigenwave dispersion of 8mm 3-folded helical corrugation waveguide is simulated using CST software. The electron beam 80kV and main magnetic field 0.67T are given by the eigenwave dispersion for Ka-band Gyro-TWT using helical waveguide. The beam-wave interaction procedure is simulated using a PIC code, in which TE11 and TE21 coupling mode transform and a right-rotating large-orbit electron bunch are obtained. The maximal output power is about 42.5kW and the maximal gain is about 29.3dB in 35GHz. The 3dB bandwidth is about 8.7% from 33GHz to 35.8GHz.