Ka-band Waveguide Cyclotron Threaded High-frequency Characteristics Of Traveling Wave Tubes And Linear Theoretical Studies

Gyrotron traveling wave tube amplifier (Gyro-TWT) is an important research subject in the field of high power microwave study from 50th to now. Because of Gyro-TWT with the characteristics of the high output power, the broad width and so on, which has vast application Values in many areas as millimeter radar,DEW,RF accelerator, and so on. During the development of Gyro-TWT, researchers found that main reasons effects the working performance of the Gyro-TWT are axial velocity spread and absolute instability, it was found that all reasons which effects the working performance of the Gyro-TWT can be removed, as long as the guide dispersion characteristics were properly changed. The spiral corrugated waveguide is a well solution to the restriction of traditional Gyro-TWT by Russian scholars Denisov; the spiral corrugated waveguide makes two modes coupling because of its special structure on angle, the Eigen modes which was coupled can couple in the broad frequency band with electron beam, which makes this Gyro-TWT possesses high power, broad bandwidth, weakly sensitivity to axial velocity spread and so on. Gyro-TWT with a spiral corrugated waveguide always has been a hot point for research by scholars from 1998. This thesis study the dispersion characteristics of the Gyro-TWT with a spiral corrugated waveguide and the beam-wave dispersion equation. The main works of this paper are listed as following:Firstly, the dispersion equation of three-fold spiral corrugated waveguide are obtained by using coupling wave theory and impedance perturbation, and modes coupled rules have been summarized based on the coupling wave theory, It was found that this waveguide posses a well mode selection characteristics.Secondly, Matlab was used in numerical computation to solve the dispersion characteristic of spiral corrugated waveguide, and the influence rules of the dispersion characteristics and mode competition of spiral corrugated waveguide were studied by geometric parameters of this waveguide. The modeling of the spiral corrugated waveguide, spiral taper and square circular waveguide have been carried out with the three-dimension electromagnetic emulation software HFSS, the modeling was simulated, so the transmission characteristics and dispersion characteristics of this guide were obtained. The HFSS simulations results are compared with the numerical one, the results of HFSS simulations agree well with the numerical results.Finally, the simplified beam-wave interaction dispersion equation of Gyro-TWT with a spiral corrugated waveguide was obtained from the equations for electronic locomotion.