Research On Material Surface-modified Of High Current Electron Beam Source Based On Marx Generator

High current electron beam(HCEB)has been widely applied to material surface modification due to its large power,high energy utilization efficiency,fast heating and cooling,parameter flexibility.By the bombardment,sputtering and energy deposition effects of HCEB irradiation,the material surface is cleaned and the comprehensive performance of the workpiece is improved.However,at present there are some limitations of HCEB.They are mainly manifested in surface modification,such as short modified depth,high faulted discharge rate,nonuniform energy distribution of electron beam and complex source structure.Therefore,it is of great significance to study HCEB.Among the current ongoing electron beam equipment,the accelerator developed by High Current Electronics Institute Siberian Branch of Russian Academy of Sciences can produce HCEB with 6 cm big spot diameter while the accelerating voltage is only 30 kV.For surface modification of ordinary steel etc.,the modified depth is only a few micrometers,far less than that of laser surface modification of steel.Therefore,it is of great practical value to study and design a HCEB source with a deeper modified layer and better stability.In this paper,aiming at the shortage of current HCEB used for material surface modification,it was proposed to use the Wave Erection Marx Generator(WEMG)to drive the cathode diode directly.This method takes advantage of WEMG features,such as compact volume,strong ability of repetition frequency and high output voltage,to increase the accelerating voltage of HCEB cathode,so as to increase the modified depth.Through theoretical analysis of the Marx generator,it can be considered as a high current electron beam cathode.Secondly,the whole HCEB system was integrally designed including five parts,i.e.,cathode discharge module,vacuum module,magnetic field pulse generator module,anode penning discharge module and control module.In these five parts,a 10-stage WEMG and the controllable pulse driver were applied as the cathode discharge module of HCEB,and the structure of the existing cathode vacuum diode bushing is optimized.The pulsed voltages of 1.8 ~ 1.9kV and 5kV were used as the power supply for the magnetic field and the anode,respectively.In the control module,the S7-200 series programmable logic controller was applied for controlling,which can meet the requirements for required pulse timing.Finally,the Pspice full-circuit simulation for WEMG and its pulse driver was carried out,and the influence rule of internal parameters on the output voltage was analyzed,thus to further verify the feasibility as the HCEB cathode and the reliability as pulse driver in the usage of WEMG.A preliminary experimental platform was built,and its pulse driver was verified by experiments.The problems in current system design were found out,which laid the foundation for further improvement of system.