Relativistic Coaxial Slow Wave Structure With A Bragg Reflector Oscillator Study

High-power microwave device is an important field in microwave technology; While relativistic coaxial inner conductor slow-wave-structure(SWS)generator is an important and has better future microwave device. The relativistic coaxial inner conductor SWS generator(RCG)with Bragg reflector is investigated on physical mechanisms and PIC simulation in this dissertation.The high frequency system in RCG that we study is coaxial inner conductor slow wave structure (SWS). As the energy of microwave will be coupled into the region of diode, the output power will decrease without reflector in front of the SWS at the end of beam injection. In order to increase the output energy of microwave, a coaxial Bragg reflector placed in front of the SWS at the end of beam injection is proposed.Firstly the parameter of reflector is calculated by software HFSS. Secondly, the effect of reflector on device is studied by PIC simulation. The physical mechanisms of the beam-wave inaction of RCG with and without the reflector are analyzed in this dissertation.The main job is the following:1. The high frequency characteristic of a coaxial inner conductor SWS is analyzed. The fields in this system are obtained by the way of field theory. The dispersion equation of this structure is deduced by utilizing the matching conditions at different interfaces. The results of dispersion characteristic of theory are in agreement with that of the simulation. By numerical calculation, the influence of the parameters on the dispersion characteristic is studied.2. The physical mechanisms of the beam-wave interaction and radiation characteristics for coaxial inner conductor SWS under different voltage of electron beam are studied by theoretical analysis combined with Particle-in-Cell (PIC) simulation. Results show that the operation status of the device transfers from backward-wave oscillations to travel-wave oscillations with the voltage of the electron beam increasing. The device has rich spectrum when it operates at theπ-mode at travel-wave oscillations; but it has a single radiation spectrum at backward-wave oscillation. It is also seen that the results of PIC simulation are in agreement with the theoretical calculations by analyzing the characteristics of the electromagnetic radiation.3. The corrugated Bragg reflector locating in the front of the high-frequency structure is proposed to improve the performance of the oscillator. The structural parameters are optimized using the high frequency simulation software(HFSS), and the influences of the reflector on device are studied using the particle-in-cell (PIC). Results show that the location of the reflectors has a great impact on the performance of the device, and there is a best location to make the radiation power remarkably enhanced.