Breakdown of short gaps at atmospheric pressure

Summary form only given. The breakdown voltage of fluids in highly divergent electric fields is typically higher for negative energisation compared to positive energisation. Volumetric space charge, created by negative energisation in a non-uniform electric field in electronegative fluids, reduces the field in the vicinity of the sharp electrode, resulting in higher self-breakdown voltages. By reducing the inter-electrode gap spacing, it is possible to reduce the effect of space charge, and this paper focuses on investigation of potential change in the self-breakdown voltage behavior for positive and negative energisation in short inter-electrode gaps. In such cases, space charge impact may be changed resulting in the different electric field screening effects, and therefore the functional dependency of the negative and positive self-breakdown voltages with the gap distance should be investigated. Potentially, breakdown in short gaps filled with electronegative gases such as laboratory air, synthetic air or oxygen will demonstrate similar characteristics (breakdown voltage, time to breakdown, and jitter in the case of a triggered switch) for energisation voltage of both polarities, positive and negative. This paper investigates self-breakdown voltages of mm and sub-mm electrode spacing in a point-plane topology at atmospheric pressure, where it is expected that space charge effects will be changed, and the behavior of self-breakdown voltages for positive and negative polarities will be different as compared with larger gaps.