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A double anode magnetron injection gun (MIG) for a 0.42 THz second harmonic gyrotron has been presented in this paper. Through design, simulation and optimization by the particle-in-cell code, a double-anode electron gun with maximum transverse velocity spread of 3.19 % is obtained, the beam acceleration voltage is 50 kV, operating current is 5.5 A and the ratio of the transverse velocity to the axial velocity is equal to 1.4. A comprehensive analysis of MIG for 0.42 THz second harmonic gyrotron is presented, and the designed electron gun well satisfies the requirement of the 0.42 THz gyrotron.

A Denisov launcher operating at 420 GHz with TE17,4 mode is designed and optimized through theoretical analysis and numerical simulations. The launcher consists of a mode converted waveguide and a helical cut. Instead of using the conventional perturbations, a sinusoid type perturbation is used in this converted waveguide. Operations of the launcher are analyzed by the coupled mode theory. The field at the output aperture of the launcher has a nice Gaussian profile distribution. The conversion efficiency is more than 98.1 %. The parasitic modes in the launcher and the aperture field profile were analyzed. The wall field of the launcher is analyzed in case that the input wave is rotating left-hand. A full 3D electromagnetic field analysis of the integrated launcher has been done. The results are in good agreement with the numerical calculation results.

Confocal gyrotron traveling wave tube (gyro-TWT) is a novel gyrotron amplifier capable of operating in higher order modes while generating high power at the same time. Confocal gyro-TWT suppresses lower-order modes at the cost of reduction of efficiency. According to the characteristics of confocal system, in this paper, we theoretically design a special magnetron injection gun (MIG) for a 170 GHz confocal gyro-TWT, and then compare it with the traditional MIG. The efficiency is found to be as high as 33 %, deservedly higher than the traditional less than 10 %. The output power increases trebly accordingly.