Research Of Vlasov Quasi-optical Mode Converter

As an important high-power microwave source, gyrotron has importance in military and scientific research, but because the output mode of the gyrotron can not be transmitted directly, the mode conversion is necessary in order to effectively apply the high power microwave from the gyrotron. Quasi-optical mode converter plays an important part in HPM transmission and launching system. In this dissertation, the quasi-optical mode conversion of the gyrotron is studied through theoretical analysis and numerical simulation in-depth, and some experiments are done for verification. The main works of the dissertation are listed as following:(1) The development and application of HPM have been described briefly, and the advantage and disadvantage of various mode conversion methods have been analyzed.(2) Using the theory of geometrical optics, the transmission of the beam in the waveguide is analyzed in detail. With the basic theory of reflector antennas and the geometrical optics, the law of the beam transmission in the Vlasov quasi-optical mode converter is obtained. In this dissertation, we designed the shape and the size of Vlasov launcher, the parabolic mirrors and the phase-corrected mirror, and researched the method transforming the millimeter wave of220GHz with TE03mode from the output of the gyrotron into a quasi-Gaussian beam..(3) According to vector diffraction theory and equivalent feed source method, some MATLAB programs are written with the parameters of Vlasov quasi-optical mode converter designed before, to simulate the distribution of the radiation field. The parameters of Vlasov quasi-optical mode converter are adjusted through the simulating radiation field results to make the output mode closer to the Gaussian beam.(4) According to the designed parameters of Vlasov quasi-optical mode converter, we manufacture the Vlasov launcher and the parabolic reflector for experiment, and the experimental results are consistent with the simulation results.