A Method to Further Improve the Efficiency of Gyrotron Traveling Tube

High output power is one of the developing directions of gyro-TWTs. A method with a down-tapered magnetic field at the nonlinear stage is introduced in this paper. A W-band gyro-TWT with heavily wall lossy loaded waveguide is simulated based on large signal to verify the feasibility of the method. Nonlinear beam-wave interaction code simulation results show that 10.3 kW more extra output power (3% efficiency) is obtained. This method is not based on sacrificing the interaction stability and can be applied to other types of gyrotron devices.