The W-band Gyrotron Traveling Wave Tube Amplifier

The high power and broad bandwidth capability of gyrotron traveling wave tube (Gyro-TWT) make it attractive coherent radiation source in the millimeter wave range. Gyro-TWT has received a great deal of attention for its bright future on the fileds of high-power radar, communication, precision guidance, material processing, particel accelerators and so on. However compared with the more developed gyrotron oscillators and gyroklystron amplifiers, Gyro-TWT is still in a very preminary state for its susceptibility to spurious oscillation, gain, efficiency, and bandwidth of gyro-TWT are still significantly below theoretical predictions. So, researches about the interaction principles and interaction structures are always the hot point of the field of high-power microwave.In this dissertation, the characteres of the interaction between electron beam and high-frequency electromagnetic field are studied. A nonlinear theory model based on single-particle theory is built for the multi-stage gyro-TWT with distributed loss. Under the guide of the nonlinear theory and particle-in-cell code(PIC), a W-band two-stage TE₀₁ gyro-TWT with distributed loss, a W-band TE₀₁ gyro-TWT based on lossy ceramic and a W-band TE₀₂ second harmonic gyro-TWT with distributed loss are designed respectively.In detail, a nonlinear theory model is put forward based on the single-particle theory. To study the design of gyro-TWT accurately, the influences of magnetic field and waveguide taper, distributed loss and velocity spread are included in the model. The calculation program of self-consistent nonlinear electron beam-wave interaction is developed.Based on the linear and nonlinear theory models, some physical phenomena of beam-wave interaction of gyro-TWT including launching loss, absolutely instability, gyrotron backward wave oscillations are analyzed and studied. Also the phase stability and the influence of velocity spread on the interaction are modeled and analyzed. Some useful conclusions which can be used to guide the design of gyro-TWT are reached.Based on the linear theory, nonlinear theory and PIC code , we have finished the design of a W-band two-stage TE₀₁ gyro-TWT with distributed loss, a W-band TE₀₁ gyro-TWT based on lossy ceramic and a W-band TE₀₂ second harmonic gyro-TWT with distributed loss respectively. The design process and the output characters are...