Design And Performance Of Auxiliary Anode For High Current Pulsed Electron Beam Source

In the emission process of high current pulsed electron beam,a conductive plasma channel between the cathode and the work-piece is needed,in order to transmit electron beam during the discharge.Penning discharge was adapted to high current electron beam source with an attempt to produce a wider and more uniform plasma channel for electron emission.As discovered in previous research,the plasma channel developed by Penning discharge with the work-piece as one of the paired cathodes was deeply affected by the surface state of the work-piece,such as its properties and roughness,etc.As a result,electron emission suffered from power shortage,irregularity of the beam shape.In this study,Penning discharge device was modified due to the effect of the work-piece.An auxiliary anode framework was introduced into the Penning discharge as one of the paired cathodes instead of the work-piece,in order to reduce the effect on discharging caused by the work-piece.In this study,three types of grid structures of hexagon,ring and square are designed as auxiliary anode.Through the detection and screening of the auxiliary anode products,the auxiliary anode size structure of the width 0.3mm of the gate wire and the thickness of the gate wire of 0.3mm is qualified,which is used in Penning discharge experiment.In the discharge experiment,it is found that the ring hole auxiliary anode have stable discharge wave and phenomenon in the discharge process relative to auxiliary anodes with the hexagonal hole and the square hole.The ring hole auxiliary anode would be the auxiliary anode for other discharge experiments.Compared with the Penning discharge phenomenon without auxiliary anode,there is a decrease in the discharge activation time and a decrease in the brightness of the plasma channel.In the condition of anode voltage 3.5kV,working pressure 3.0×10^-2Pa,magnetic field 0.16T,circular hole auxiliary anode with grounding and no simulated work-piece,the discharge phenomenon is first appeared.It is proved that the new beam source with installation of auxiliary anode can appear Penning discharge phenomenon without the work piece.Compared with the Penning discharge phenomenon without auxiliary anode,there was decrease in the discharge activation time and brightness of the plasma channel.The effects of the auxiliary anode voltage,Penning anode voltage,magnetic field intensity,vacuum degree,auxiliary anode resistance,anode current limiting resistance and auxiliary anode structure on the Penning discharge process were analyzed under the conditions of different electrical parameters.According to the experimental results,the discharge waveform and the phenomenon of the ring hole auxiliary anode are more stable under the same experimental conditions;Under the condition of anode voltage 4.8kV,vacuum degree 6.8×10^-2Pa,and magnetic field intensity 0.18T,the discharge stability is the best,so it can be used as the ideal optimization parameter under the experimental conditions;Through discharge experiments,it is found that with the increase of current limiting resistance,auxiliary anode resistance and auxiliary anode potential,the velocity of plasma is accelerated,the activation time of discharge is shortened and the stability of discharge increases.