Research And Development Of The15kW/60kV Electron Gun

Along with the rapid development of technology in aviation、aerospace and other fields in china, more and more new materials need to be connected by welding, and the requirements of weld quality is also improved gradually. As a new technology of fusion welding developed in recent decades, electron beam welding technology greatly meets the needs of the modern industrial welding for the characteristics like larger ratio of welding seam depth and width, minimum part distortion and higher energy density. However, for the reason that domestic power of electron gun is too small to reach the requirements of welding the thicker section parts, electron beam welding machine in the domestic fields like aviation、aerospace and so on are heavily dependents on imports. So it is of great significance and huge application value to research such a high-power electron gun.The design idea of high-power electron gun in this thesis is to find a way to increase the beam power based on the structure of6kW/60kV welding electron gun of directly heated type.Firstly, the trajectory of the beam is simulated based on the theory of electronic optics and precision machinery with the finite element analysis software of SOURCE, and the rationalities of some relevant electrode structure is testified according to the simulation result and theoretical calculations, at last, an electrode structure which can produce15kW power beam is developed.Secondly, some important influence rules of electrode is raised by the corresponding research about these following important factors includes the electrode area of the cathode emission, polar distance and gate bias voltage. Beam spot diameter is an important index for the performance evaluation of electron gun, in this paper, several important physical factors which effect the electron beam spot are discussed, the result that the actual electron beam spot is in a reasonable range is proved through the corresponding theoretical calculation.Thirdly, the whole3d model of the new electron gun is drawn, it is composed of the high voltage insulator、water cooled, electrostatic lens, turbo molecular pump system, light optical viewing system, isolation valve and magnetic lens. The most difficult design part of the electron gun is the design of the electrostatic lens (that is, the electrode structure) which includes the choice of emission area cathode, the computation of distance between cathode and anode, the adjustment of grid cup and anode, the change of the grid cap shape and so on. As the power density increase, a lot of heat will be produced in the cathode and anode after a long time work of electron gun, which will cause its own deformation, to avoid such deformation, water cooling of cathode and anode is added. To solve the problem that the lens of the optical observation system is easy to be polluted by the metal vapor, a new electrode structure is designed in this article, which greatly extent the period of replacement cycle of the lens.Finally, the15kW/60kV electron gun was placed on the experimental electron beam welding machine, and a series of welding experiments are performed and the results show that such performance parameters as the weld quality, vacuum degree and so on have reached the design goal, and no unusual phenomenon in the process of welding happened, the stability of system is so high.