Study Of Industrial Electron Gun Observation And Imaging Technology Based On Secondary Electrons

The electron beam is a high-energy density particle beam that is a primary factor in determining the quality of electron beam welding processes.During electron beam processing,technicians usually are required to use observation methods to monitor the processing situation in the vacuum chamber in real-time in order to ensure processing quality.At present,the most widely used observation method is optical observation.However,optical lenses are prone to metal vapor deposition during the welding process,and the optical imaging resolution is low,which can cause inconvenience for continuous observation of welds and alignment.This study delved into the secondary electron observation and imaging technology of industrial electron guns.It analyzed the corresponding relationship between the secondary electron yield and surface morphology,and summarized the changes in secondary electron yield of typical morphological features of workpieces,and obtained valuable research conclusions for using secondary electron signals to reflect the surface morphology information of workpieces.The main research content of this article includes the following four aspects:(1)To gain a deeper understanding of the mechanism of secondary electron generation,the scattering motion trajectory of an electron beam in a workpiece is studied,and various elastic and inelastic scattering cross-section formulas proposed by previous researchers are analyzed.Additionally,a secondary electron emission model suitable for this subject is established thorough Monte Carlo methods.MATLAB software is used to simulate the model,and the laws and characteristics of secondary electron emission are summarized through the simulation data results.(2)To further study the laws and characteristics of secondary electron imaging,work out a formula for calculating the imaging signal current is derived,and analyze the formation principle of secondary electron image contrast,this article focuses on the morphology contrast of secondary electrons.Taking triangular and rectangular grooves as examples,a mathematical model is constructed to investigate the corresponding relationship between surface morphology parameters and secondary electron signal current,and the change law of secondary electron image contrast under different morphology characteristics is quantitatively analyzed.(3)This paper studies the mechanism of secondary electron emission and the generation mechanism of secondary electron morphology contrast,and proposes a control strategy for the industrial electron gun secondary electron observation imaging system,and proposes corresponding solutions and optimization measures for key problems that arise in the actual imaging process.(4)Conduct experimental verification on the research content of this article,using an industrial electron gun to generate a small beam and scan different morphological feature areas,and real-time detect the changes in the waveform of secondary electron signals through an oscilloscope.The experimental results show that there is a corresponding relationship between the secondary electron signal intensity and the surface morphology of the workpiece.Based on the effective collection and processing of these signals,high-quality surface morphology images can be obtained.The phased research results of this paper provide a valuable reference for the application and promotion of secondary electron imaging technology in industrial electron gun image observation systems.