Design And Simulation Of Deflection Mechanism Of Vacuum Electron Beam Furnace

With the development of advanced science and technology, such as aerospace, atomic energy, automation and so on, the demands for high-end materials put forward higher requirements for melting equipment. Compared with other melting equipment, the electron beam furnace not only has high energy density heat source, but also can refine the materials in the process of melting. So it can gain high purity metal and alloy. Core technology of electron beam furnace is control of deflection angle of electron beam and diameter of electron beam spot. However, the control of deflection angle of electron beam and diameter of electron beam spot is on the basis of better uniform distribution of deflection magnetic field. The better the uniformity of magnetic field distribution, the smaller the diameter of electron beam spot will be. The above contents are the purpose of this thesis.In this thesis, the research target is250KW vacuum electron beam furnace. Design ideas of original structure of deflection construction is deeply understood via the study of distribution theory of deflection magnetic, uniform magnetic theory, electron beam scanning theory and relationship between distribution rule and coils structure and so on, which provides basis for the simulation and analysis of deflection magnetic of250KW electron gun.Model of electron gun and deflection structure of the250KW electron beam furnace are constructed and analyzed by CST simulation software. The relationship between distribution of magnetic induction line and various parameters such as coils turns, current, and the shape of coils are also analyzed. Based on this analysis, the parameters of electron beam deflection structure are optimized. Optimization results show that:uniformity of the distribution of magnetic induction line gradually becomes better with the decease of the triangle coefficient. Second focus coils have an effect on deflection and spot diameter of electron beam. The shorter the focal length of second focus, the smaller the spot diameter of electron beam will be, but the change of cross section of electron beam is extremely big; he longer the focal length of second focus, the bigger the spot diameter of electron beam will be, and the change of cross section of electron beam is very small. The current also have an effect on uniformity distribution of deflection magnetic field. But the effect is so small that can be ignored. There are close relationship among deflection angle、spot diameter、the focal length of second focus and triangle coefficient of deflection coils, through simulation and analysis. The deflection angle of original deflection structure is45°,the position of focus is in the middle of saddle coils. The analysis of simulation results show that:reducing triangle coefficient is the best methods that maintain the spot diameter better, and increasing the focal length of second focus can ensure the maximum deflection angle of electron beam. As a result, the two factors of triangle coefficient and focal length of second focus can be combined to make the diameter of electron beam spot better in the case of remaining the angle of the electron beam deflection unchanged.