Traveling-wave Tube Electron Optical System Integration Design

Traveling wave tubes (TWTs) is a high-gain microwave / millimeter-wave power amplifiers. It demonstrates the important and irreplaceable role in the modern military electronic equipment. In the TWTs, the electron-optical system is formed by three components, which are the electron gun, Periodic Permanent (PPM) Magnetic Focusing System and depressed collector, and involve in the field of injecting the electron beam, shaping and maintaining the electron beam, and collecting the electron bean, so it is an important part of TWTs. The quality of electron beam, which offered by electron optics system, determines fundamentally the TWTs'crucial parameters such as efficiency, gain, working stability and noise characteristic etc. Electron-optical system's design is important aspect design of the traveling wave tube.Theory and computer simulation laboratory has done some research on the theory of electron optics system. In the CAD software, the electron optics system includes three modules, which are the Electron Gun module UESTC_Gun, the Focusing system UESTC_PPM and the Collector module UESTC_MDC. The paper studied the principle of the electron optics system, and used the modules of the TWTCAD to develop the environment of the electron optics CAD system. In the system, there are over 12,000 lines C++ codes wrote by me, and about 30,000 lines codes modified by me.At the beginning, the paper made a brief description of the electron optical system development process and description of the research actuality of the electron optical system at home and abroad. At the second part of the paper, explained the numerical method of the electron-optical system, mainly including the method of calculating the electrostatic, the numerical method of calculating static magnetic field, the method of calculating tracks, and the method of calculating the distribution of space charge.In the developed environment of the electron optical system, it modified the function what is used to judging the point whether is in the electrode. In the process, it used the logical coordinate to judge instead of physical coordinate, solved the problem what would be happened occasionally. According to the theoretical foundation and the theory of incorporate electron optics model, the EOS CAD system established an integrated simulation model of electron-optical; it could simulate the whole process of launching electron from gun, maintaining and focusing the electron by PPM Focusing System, and collecting the electron by collector. Meanwhile, the system could calculate the magnetic field leaked by PPM for the Gun calculating module and the collector module, improve the space magnetic field calculation of gun module and collector module. The EOS CAD system could also respectively simulate the gun computation, PPM computation and the collector computation. The EOS CAD system inherited the advantages of the original computation module: UESTC_Gun, UESTC_PPM and UESTC_MDC, including friendly interface, simple operation, fast computation and the visualization of the computing process and result, also added some new characteristics, such as the saved data function, and the standardization of software framework.