Ku Band Spiral Corrugated Waveguide Cyclotron Frequency Characteristic Of Traveling Wave Tube And The Nonlinear Theory Research

Gyrotron travelling wave tube (gyro-TWT) plays an important role in radar, military communication and microwave weapon for high power and board band. Recent years, many research groups in the world had devoted much focus on gyro-TWT which includes large and small orbit types. Since1970s, a myriad of research and experiments had been developed in USA and Russia, and mainly in NRL, UC Davis, MIT and Maryland of USA and IAP of Russia. In the design of gyro-TWT, it is found that the helical electron beam quality and absolute instability had a great influence on the gyro-TWT characteristic, however it can be improved or overcome by adjusting the waveguide dispersion curves. In order to reduce the influence due to velocity spread, a novel beam-wave interaction circuit helical corrugated waveguide was put forward in gyro-TWT by G. G. Denisov and the large orbit CUSP electron gun was also used. Analysis and simulation turn out that it is not sensitive to the velocity spread and can broaden the bandwidth.In this paper, we mainly study the dispersion curves and non-linear self-consistent theory of a Ku-band helical corrugated waveguide gyro-TWT. The remainder of this paper will be organized as followed:1, On the basis of perturbation theory, the coupling wave equation, coupling coefficient and dispersion curves are derived with coupling wave method and analyze the dispersion characteristic and spurious mode due to waveguide structure parameters.2, Simulated the helical corrugated waveguide with the HFSS code, and analyze its cold field characteristic such as S parameters, dispersion curves and EM field distribution. At the same time, simulation agrees well with the numerical calculation results by MATLAB.3, The beam-wave interaction process of HCW gyro-TWT is studied with the self-consistent non-linear theory. In this process, RF field will modulate the helical electron beam (HEB) and lead HEB to bunch. At the output coupler, the HEB will exchange its engery to the RF field to finish amplification. In this chapter, we derived the electron movation and beam-wave equations, and simplify them.