Probability distributions for the breakdown voltage between closely spaced electrodes on insulating surfaces

Abstract

Probability distributions for the breakdown voltage between closely spaced electrodes (≊10 mils) on insulating surfaces are studied with results from a Monte-Carlo simulation. The probability distributions, experimentally measured to be bimodal under certain conditions, are found to be characterized by the number of ionizations per primary electron emitted at the triple junction that is required to initiate the electron avalanche. Bimodal distributions represent a transition region between low variance and high variance normal distributions requiring low and high multiplication coefficients, respectively, for the avalanche to occur. Conditions of moderate preionization and low electron loss rates to the insulating surface (e.g., large secondary electron coefficient) are found to lower the breakdown voltage and reduce bimodal distributions to single normal distributions.