Simulation and Experiment of a Ku-Band Gyro-TWT

Design techniques and experimental results are presented on a Ku-band TE₁₁ mode gyro-traveling wave tube. The hot test of this amplifier gives more than 153-kW output power, 2.3-GHz bandwidth (14%), 41-dB saturated gain, and 20% efficiency driven by a 63 kV, 12-A electron beam with a pitch angle (v_tv_z) of 1.2, and velocity spread of 5%. A linear polarized TE₁₁ mode input coupler is used to introduce the input power. The stability of the amplifier from oscillation, including both the operating TE₁₁ mode and the backward wave TE₂₁ mode, has been investigated with linear codes, nonlinear selfconsistent theory, and 3-D PIC CHIPIC simulation. To suppress the potential gyro-backward wave oscillator interactions, the high frequency circuit is loaded with lossy ceramic rings. The lossy structure is optimized by nonlinear theory and 3-D PIC simulation. A low velocity spread magnetron injection gun is designed with a new structure.