Effects of the electromagnetic power coupling on vacuum breakdown

Vacuum breakdown is a key factor limiting the performance of applications that utilize vacuum for insulation. The surface electric field has been regarded in previous studies as the only parameter that determines the occurrence of a vacuum breakdown, for a given surface condition. However, several recent works indicated that the ultimate limit for a vacuum breakdown also depends strongly on the electromagnetic power available in the system to be delivered at the breakdown site. In this work, we study this dependence both experimentally using a pulsed DC system and by numerical simulations using a particle-in-cell (PIC) model. By varying the circuit impedance which includes resistance and capacitance, we controllably limit the power coupled to the vacuum discharge gap. The experimental results show that the breakdown voltage increases with increasing impedance, i. e. with increasing circuit resistance and decreasing capacitance; The PIC results showed that a minimum current is required besides the critical voltage during the initiation of the breakdown plasma, and the breakdown voltage is defined by the circuit impedance and the critical power loaded to the gap just before the breakdown, which is in agreement with the experimental results.

Automated summary

This study investigates the factors affecting vacuum breakdown through experimental and numerical simulation methods. The experimental results show that increasing circuit impedance can enhance the breakdown voltage. The numerical simulations confirm that circuit impedance and the critical power loaded to the gap are crucial for determining the breakdown voltage, which is consistent with the experimental findings.