Breakdown phenomena across micrometer scale surface gap under negative voltage application

With the miniaturization of electrical devices, the insulation width and the separation between electrodes have been accordingly reduced. Consequently, electrical breakdown across micrometer-scale gaps is of great practical interest for insulation design. In this paper, electrical breakdown across micrometer scale surface gap in atmospheric air was investigated under inhomogeneous field. The breakdown was measured under negative impulse voltage and the generation and movement of neutral and charged particles were simulated based on PIC-MCC (particle-in-cell with Monte Carlo collision). The result shows that the breakdown phenomena across micrometer scale gaps is mainly determined by field emission current from the cathode surface, similar to the discharge process in vacuum. The positive ions generated by collision of electrons to neutral particles enhance the electric field near the cathode, resulting in the increase of the field emission current from the cathode.