Effect of Space Charge on Vacuum Breakdown Characteristics of Copper Nanoelectrode

In order to study the theoretical mechanism and influencing factors of vacuum breakdown of nanoscale cathode emitters, an advanced electrodynamic coupled molecular dynamics and particle simulation calculation method (ED-MD-PIC) is adopted in this paper. By comparing the difference of electric field distribution in vacuum environment and space charge effect，the effect of space charge effect on the vacuum breakdown characteristics of nanoelectrodes with different sizes was studied. Under the space charge effect, the minimum local electric field intensity that can cause vacuum breakdown of copper nanoelectrode is about 12 GV/m. The space charge effect of copper nanoelectrodes of different sizes is different. With the increase of electrode size, the space charge effect exerts more effect on the applied critical electric field of vacuum breakdown. As electrode size decreases, the space charge limits electron emission more significantly. The effect of space charge effect is more reflected in slowing down the pre-breakdown process and increasing the vacuum breakdown delay, and the impact on the breakdown threshold is smaller.