Research On Electron Beam Deflection Technique And Dynamic Focusing Of Industrial Electron Gun

As a kind of high energy density particle beam,electron beam is widely used in all kinds of modern processing with high requirements.The electron beam deflection and focusing accuracy will directly affect the quality of electron beam processing,especially in the electron beam deflection scanning with large Angle,the focus of the electron beam will appear defocus phenomenon due to the influence of such factors as aberration,which affects the focusing performance of the electron beam.In order to improve the processing quality of the electron beam and to control the electron beam accurately,the electron beam can realize the dynamic adjustment of the focusing current at the same time of deflection scanning.In this paper,the industrial electron gun system with power of 6k W and acceleration voltage of 60 k V is taken as the research object to study the dynamic focusing of electron beam deflection scan.The main research results are as follows:(1)The trajectory of the electron beam in the electromagnetic field was studied,the mathematical model of the trajectory of the electron was established,the trajectory of the electron was simulated by MATLAB software,and the causes of aberration such as spherical aberration and astigmatism were analyzed.The method of dynamic focusing of deflection scanning was proposed to reduce the influence of the aberration on the trajectory.(2)According to the electron gun structure,calculated the basic parameters of electron gun and electron beam profile parameter values,analyses the shield type magnetic lens in the magnetic field near the pole shoe shape and boundary conditions,ANSYS software to simulate the pole shoe near the vector magnetic potential distribution,in-depth study of electromagnetic coil current focus on the influence law of size,It is found that the working distance and focal size of the electron beam can be changed by adjusting the focusing current.(3)Based on scanning electron beam deflection dynamic focusing accuracy,analyze and study the dynamic deflection of the electron beam scanning is focused on the fixed current theory,sets up a dynamic focusing on the control strategy of scanning electron beam deflection and dynamic is focused on the two dimensional array,in combination with calculated parameters of electron gun and established the electron gun structure using CST software simulation model simulation of the electron beam movement trajectory,The existence of beam focus defocus and the effect of dynamic focusing correction current on the size of focus in the electron beam deflection scanning are verified.(4)Based on the simulation results,the feasibility of the theoretical scheme is verified through experiments.Focus of electron beam size and deflection Angle as well as the relationship between focusing current,dynamic focus electric flow deflection scanning track and the dynamic correction aberration experiment,experiment results show the dynamic focusing deflection scanning current control strategy can effectively improve the deflection error and large deflection Angle of electron beam under the defocusing.