Design And Optimization Of Quasi Optical Mode Converter For Gyrotron

With the development of high power microwave technology and the ITER project, development of high power microwave source towards higher power and higher frequency, and high power microwave source has been paid more and more attention by people. For the higher order modes in the gyrotron, the common waveguide mode converter is no longer applicable, development of quasi-optical mode converter has become a trend. The research on the optical mode converter in foreign countries has become more and more mature, and the research of this technology is just started in China, but in recent years the country has increased its attention to the technology. This paper studies high-power gyrotron(MW output power level) of the quasi-optical mode converter.This paper first analyzes the research background and significance of the thesis, the working principle and application of the gyrotron are introduced briefly, the waveguide mode converter and quasi optical mode converter are analyzed in detail. A brief introduction to the Gauss distribution of the target field distribution, and the distribution characteristics of the Gauss base mode field are analyzed. The beam propagation characteristics of circular waveguide launcher is analyzed based on the geometrical optics theory. The working principle of Vlasov launcher and Denisov launcher are deduced, and designed to work with the same frequency and the same mode of operation Vlasov launcher and Denisov launcher, comparison of characteristics is carried out. Based on the theory of geometrical optics, the structure of quasi elliptical cylindrical mirror and elliptical parabolic mirror is constructed, vector diffraction theory and the theory of phase correction are analyzed in detail, and the scalar conversion efficiency and the vector conversion efficiency are introduced.Combining numerical simulation program and electromagnetic simulation software, a working frequency 140 GHz, working mode Denisov TE22,6 quasi optical mode converter is designed, through the numerical simulation of structure optimization of Denisov launcher and mirror system, numerical simulation and electromagnetic simulation are also carried out, the comparison shows that the numerical simulation results are consistent with the electromagnetic simulation results. The output window at the field distribution in the amplitude and phase are analyzed to obtain a waist radius of the field distribution of the fundamental mode Gaussian content, phase distribution, the conversion efficiency and other parameters characteristic. Finally at a fixed quasi-optical mode converter structure and high frequency gyrotron structure, when the eight mode satellite Denisov launcher as incentive effect on the field distribution at the output window.