Nonlinear analysis of a Ka-band second harmonic distributedloss gyrotron traveling wave amplifier

The nonlinear theory of the Ka-band second harmonic gyrotron traveling wave amplifier with two-stage loss waveguide was studied. The two-stage loss waveguide consisted of a loss waveguide and a copper waveguide. The operating parameters of the 35 GHz TE02 mode second harmonic gyro-TWT were determined by stability analysis, and the radius of the waveguide is 1.02 cm, the working voltage of electron beam is 90 kV, the working current is 25 A, the magnetic field is 0.642 6 T, and the transverse-longitudinal velocity ratio is 1.2. The effect of several factors on the amplifier performance, including operating current, waveguide loss and velocity spread, were analyzed through simulation. The results show that the loss waveguide can effectively restrain the unwanted modes in this structure, thus