Investigation On A Large Radius And Coaxial Relative Oscillator With High Efficiency And Long Pulse Output Of X-band

The high-power microwave oscillator technology based on the coaxial slow-wave structure combined with the large-radius structure,which not only helps to improve the device power capacity and conversion efficiency,but also has lower impedance,simpler operating mode composition,and lower magnetic field.This technology with these advantages is expected to solve the contradiction between high efficiency and long pulse working of high-power microwave generating devices,and other practical applications.The high-power microwave generating devices operated in the X-band contour band,can effectively increase the pf² factor of the system and prolong its working distance.In addition,long pulse high power microwave output realized at a certain output power level,can further increase the pulse energy of the output microwave and enhance the effect of the system.Therefore,it is of great significance to study the X-band long-pulse high-power microwave oscillator.In this paper,an X-band large-radius coaxial relativistic oscillator is proposed and related research is also carried out.Because the relativistic oscillator is complex,the analysis is based on both Cerenkov theory and transit radiation theory.The research content of the thesis mainly includes the following aspects:Firstly,based on Cherenkov radiation theory,the theory and characteristics of X-band relativistic oscillator are theoretically deduced and studied.By using electromagnetic field and mathematical physics method,the dispersion equation of TM mode in the relativistic device slow-wave structure with coaxial deep cavity is derived.Combined with MATLAB software,the dispersion characteristics of the relativistic device slow-wave structure with coaxial deep cavity is studied,the difference between infinite periodic cold cavity structure,finite periodic hot cavity structure and numerical solution is compared,and the influence of geometric parameters in the slow wave structure on the working frequency of the device is analyzed.It provides a theoretical basis for the subsequent structural design and has a very important guiding significance for further research on X-band relativistic oscillators.Secondly,based on the theory of transit radiation,the theory and characteristics of the device are deduced and studied.The pattern matching method is used to solve the electromagnetic field distribution and resonance frequency of the electron beam passing position in the transit cavity,and the influence of structural parameters on the resonant frequency is analyzed.The small-signal theory is used to solve the electron beam coupling coefficient and the normalized conductance.The mode selection of the modulation cavity and the working voltage range of the crossover device are analyzed and discussed.On the basis of theoretical analysis and numerical calculation,the particle simulation of the X-band relativistic oscillator is carried out.Under the condition of electron beam voltage of 628 kV,beam current of 16 kA and guiding magnetic field of0.7 T,it is obtained the 3.9GW high-power microwave output at 9.24 GHz and has an efficiency of about 39%,the device operating mode is TM₀₁ mode,and the saturation time is about 20ns.It can be seen that this large-radius coaxial structure device has the advantages of higher power,higher efficiency and longer pulses than both radial devices and non-coaxial devices.At the same time,the paper analyzes the effects of various structural parameters and working parameters on microwave output.Finally,the preliminary experimental design of the device is carried out.