Research On High Voltage Generation And Control Of High Current Pulsed Electron Beam Source

Non-relativistic high-current pulsed electron beam source is a kind of high-energy pulsed electron beam generating device,which can obtain high-energy electron beam at relatively low voltage.When the beam irradiates to the target material,the surface of the target material can be instantly or rapidly melted,evaporated,and cooled and solidified,resulting in physical properties that cannot be formed in the steady state.Therefore,high-current pulsed electron beam source is of great value in surface modification of materials such as finish and bio-compatibility.However,according to the principle of non-relativistic high-current pulsed electron beam source,intense pulsed magnetic field,high-power pulsed anode and cathode current will be generated during the operation of the beam source.The above strong pulsed magnetic field and high current may strongly interfere with the weak current control system.At the same time,it is difficult to accurately control the high pulsed magnetic field,high power pulsed anode and cathode current,so that the irradiation of target material can not achieve the ideal effect.In addition,the voltage level of the beam source is high,especially for the control system,the insulation reliability is very low.In view of the above shortcomings,it is necessary to develop an electron beam source equipment with stronger anti-interference,more flexible synchronous control and better irradiation effect of beam source.In this paper,a new generation of pulsed electron beam source is designed on the basis of fully understanding the working principle of non-relativistic intense current pulsed electron beam source.The beam source is composed of PC,30 k V high voltage DC power supply,2k V high voltage DC power supply,energy storage capacitor group,pulse trigger driving circuit and secondary discharge circuit,vacuum diode,vacuum system and so on.The PC uses wireless communication module to carry out wireless MCU networking and control for HVDC source and trigger driver circuits.The hardware structure of the system is simplified.2kV and 30 kV high voltage DC power supplies are designed to supply primary energy storage for each capacitor group respectively.Each power supply includes main circuit,drive circuit and control circuit respectively.The main circuit is composed of rectifier filter circuit,half-bridge inverter circuit,high frequency isolation transformer,and high voltage rectifier filter circuit.PC via wireless control circuit,the control of PWM drive circuit,PWM drive circuit to control signal amplification,plastic as the drive signal,drive half bridge inverter main circuits of the power electronic components,the former level to the high frequency inverter dc,and,in turn,isolation booster and high pressure high-frequency rectifier,filter,give priority to the dc output voltage capacitor charging.At the same time,the voltage divider is not only used to detect the output voltage value,timely closed-loop feedback to the control circuit,stable adjustment of the output voltage,but also for the important components set buffer,over voltage,over current protection and other links,to ensure the stable and safe operation of the pulse power supply.The thyristor is designed to trigger the drive circuit,which drives the discharge of the storage capacitor guiding the magnetic field,anode and cathode circuits.The trigger drive circuit has built-in wireless isolation,optical isolation,pulse transformer magnetic field isolation and other triple isolation,and adopts one-way control mode from PC to wireless MCU,so that the control system has higher voltage resistance and stronger disturbance resistance under strong pulse electromagnetic field.The designed synchronous control system makes full use of the internal resources in single-instruction periodic MCU,and adopts the control method combining large cycle and fine delay,which can precisely control the synchronous time of magnetic field,anode and cathode discharge.The accuracy of discharge synchronization time difference is within 62.5nanoseconds.The important units in the designed system,such as the trigger control system software,hardware circuit,physical production and experiment.The experimental results show that the new generation of beam source can control the generation of high voltage well,and the control of synchronous trigger can achieve the expected goal.This topic has great reference significance for the development and practical application of pulsed electron beam source.