S-band Plasma Coupled-cavity Traveling Wave Tube High-frequency Structure Of The Theoretical Design And Experimental Study

Recently, it was found experimentally that injected plasma into the microwave apparatus enhanced the interaction efficiency and the output power much more than the vacuum cases. Plasma also can improve the transmission quality of electron beam as much as make beam transmission without a guiding magnetic field. All-Russian Electro-technical Institute (VEI), Moscow, Hughes Research Laboratories and University of Maryland has reported their achievements in this area of research. At present, much research in this area has been carried out in Institute of High Energy Electronics, University of Electronic Science and Technology of China.In this dissertation, the characteristics of the plasma-filled coupled-cavity high-frequency structure are analyzed and simulated, and the cold-test study of the S-band plasma-filled coupled-cavity chain is presented.The general method of the circuit model is regarded as unsuitable for the study of the magnetic plasma-filled coupled-cavity slow-wave structure. We utilize the dyadic Green's functions and the method of matching boundary conditions to establish the dispersion equation of the plasma-filled coupled-cavity slow-wave structure. And then we analysis on-axis interaction impedance when plasma fill.A program has write for calculating the features of the coupled-cavity slow wave structure, which is based on the method above, and the three-dimensional electromagnetic field simulation software package HFSS (High Frequency Structure Simulator) are used to compute the cold-test parameters-dispersion and on-axis interaction impedance for the coupled-cavity chain. To use the periodic boundary conditions, the coupled-cavity slow-wave structure only needs to establish one cycle model, and then it can be simulated, greatly reducing the amount of computation. With the software rich post-processing features, we use definition to compute the on-axis interaction impedance.Analysis TWT dispersion different measurement principle and method, and then we select one from the most simple and effective methods. An S-band plasma-filled coupled-cavity chain is designed according to the simulation optimized results. A cold-test is carried out to demonstrate that the results are in agreement with the program algorithm results.