Study And Design On Control System Of Electron Beam Generator

Pulse electron beam is widely used in the field of material surface modification because of its high energy density,low reflectivity,high efficiency and fast heating and cooling.Aiming at the problems of high voltage discharge control circuit,such as strong electromagnetic interference,insulation damage,time sequence control of magnetic field,anode and cathode,a pulse electron beam source and its time sequence discharge control system with higher stability,lower failure rate of low frequency repetitive discharge and simpler control are proposed.After analyzing the theory of pulse forming network in electron beam,combined with the design experience of pulse electron beam source at home and abroad,the main control system of electron beam based on the combination of radio frequency communication and optical fiber communication is proposed.The peripheral circuit and photoelectric conversion circuit of core chip are designed in detail,and the software flow of sequential discharge control program is given.The trigger drive circuit of the discharge switch thyristor in the pulse forming network is analyzed in theory and calculated in hardware.It is verified by simulation and experiment that the trigger drive circuit can reliably and quickly trigger the high power KK fast thyristor in the control system.According to the requirements of the surface modified pulse electron beam source,combined with the basic theory of the switching power supply,a high-voltage DC auxiliary switching power supply for the pulse forming line triggered by the magnetic field,anode and cathode is designed.The power supply uses tps28225 as the PWM controller,half bridge inverter and full bridge rectifier DC-DC boost structure,with the output of up to 2KV DC high voltage,to charge the energy storage capacitor.The output terminal of the power supply adopts a reverse high voltage suppression circuit composed of varistor,soft recovery diode and high power current limiting resistor,which eliminates the harm of pulse high voltage to the power supply and control system.In order to reduce the electromagnetic interference of electron beam source,the source and propagation effects are analyzed.The electromagnetic field distribution of the beam source under the strong electric pulse is obtained by the electromagnetic field simulation software based on the finite integral method,and the influence of the pulse magnetic field on the beam source is analyzed.The results show that the interference of the control system of the electron beam source is not only from the high frequency signal interference of the power source itself,but also from the influence of various discharges in the working cavity of the electron beam on the control system through channels such as discharge circuit or other media.Then,the suppression measures of the electromagnetic interference are considered from the aspects of hardware and software.The control system of the pulse electron beam source designed in this paper is verified by the combination of simulation and real object,which proves that the design is reasonable;the high-voltage DC auxiliary switching power supply is compact in structure and easy to use.It can basically meet the performance requirements of material modified high current pulsed electron beam equipment,and has great reference value for further development of pulsed electron beam equipment with higher power density and greater penetration depth.