Development Of High Energy And High Flux Argon Ion Gun

Large-aperture aspheric mirrors are a core component in space science research,thermonuclear fusion,intense laser emission and astronomical optics,and ion beam polishing is one of the main techniques used in aspheric mirror fabrication.The argon ion gun typically used in the laboratory as a surface treatment has an energy of between several hundred and two thousand electron volts and is sprayed onto the surface of the sample to the stripping of the surface atomic layer is achieved.To achieve ultra-precise and rapid polishing of the surface of large-diameter optical components,a higher energy and larger beam flow argon ion gun is required.In order to make up for the shortage in the field of ion beam polishing in China,based on the advantages of various international ion guns,we have developed and produced a high energy and high beam current argon ion gun suitable for the high precision and rapid polishing of the modified layer of silicon on the surface of large diameter silicon carbide aspherical mirrors.Ar ionization is realized by filament and anode grid,Ar+energy is determined by anode voltage,and Ar+emission and focusing are realized by extractor and electrostatic lenses.When conducting the simulation,the initial model of the argon ion gun focusing lens is determined first,and then the key parameters of the ion gun focusing lens are optimized by simulating the argon ion beam trajectory through theoretical calculations with the help of finite element analysis software CST.The design of the size and position of the focusing lens was completed under the condition of ensuring the best parameters of the lens.The whole design can guarantee the best Ar ionization and transmission.The materials in the Ar ion gun are suitable for ultra-high vacuum,and the dimensions are determined to avoid vacuum discharge.In order to verify the feasibility and effectiveness of the argon ion gun design,the group built an ultra-high vacuum system in order to conduct performance testing experiments.The test results show that the Ar+energy and beam flux can reach 20 ke V and 50μA respectively at 30 mm working distance and Ar partial pressure 1.2×10^-2Pa.The beam size can be continuously adjusted from 19 mm to 24 mm.The measured indexes of this high-energy,high flux argon ion gun fully meet the design standard,and the small size allows it to be mounted on a vacuum multi-dimensional displacement table for a wide range of motion to achieve high-vacuum surface polishing of large-diameter optical components.The successful development of this high-energy and high flux argon ion gun improves the comprehensive technical level of China in the field of small high-energy large-beam flow argon ion gun and promotes the development of domestic ion beam polishing equipment.