Study On High Frequency Cavity For Gyrotron

High frequency, high power is an important direction for the development of gyrotron today. With gyrotron operating frequency further improved, it requires gyrotron working in higher-order modes in order to effectively avoid machining of the cavity. The more mode number, the more competition mode. Therefore, the mode competition has been a gyrotron research focus. It is the first to clear coupling mechanism between the modes by the coupled-wave theory. The final the structure of cavity which has a potent to restrain competition mode has been design though optimizing. With the structure of the cavity, a perfect group of electrical parameters and design parameters has been got through continuous optimization of the relevant parameters of the electron beam voltage, current, electronic horizontal and vertical velocity ratio, magnetic field. This structure can provide valuable reference for future research. The main work of this article are shown as follows:1.With the multi-mode self-consistent nonlinear theory of gyrotron, electrons motion equation and powered and unpowered first-order transmission line equation have been deduced detailed. First, coupling mechanism of parasitic mode has been studied by multi-mode self-consistent nonlinear equations. The first-order transmission line equation shows that the coupling between the modes can only be reduced but not disappear, which is determined by the characteristics of the transmission line equation. From the perspective of cavity design,, the coupling coefficient is reduced as much as possible only by changing the cavity structure in order to effectively inhibition competition mode. Based on the above reasons, the changes in the structure of gyrotron resonator are attempted.2. The existing three-dimensional electromagnetic simulation software which is not suitable for optimizing the structure have a very long calculation period for millimeter-wave resonator. The cold and hot cavity computer simulation program which is based on Matlab have been compiled by multimode self-consistent nonlinear theory. The Program have been certified correctly with the calculation results of three-dimensional electromagnetic software and related reports of the specific parameters of the resonator.3. The gyrotron working at a voltage of 77kV, an electron beam current of 38A, frequency of 170.08GHz, working mode of TE28.8, the magnetic field of 6.708T, electronic horizontal and vertical velocity ratio of 1.6, the guiding center radius of 8.28mm, has been successfully designed with the calculation program. Throughout the design process, a lot of linear and nonlinear analysis have been done. A reasonable set of electrical parameters is determined through continuous optimization of the relevant parameters, finally, the output power could be over 1.32MW with the efficiency of 45.2%.