Electron avalanche and surface charging on alumina insulators during pulsed highhyphen;voltage stress

摘要

This paper describes a model for insulator surface charging in highhyphen;voltage ceramic vacuum diodes. The model involves electron emission from the insulatorhyphen;cathodehyphen;vacuum junction followed by electron avalanches on the insulator surface which leave the wall positively charged. Experiments were performed to measure (i) the triplehyphen;junction (cathodehyphen;vacuumhyphen;insulator interface) emission and its relation to the initiation of the avalanche, (ii) the dynamic current in the avalanche, and (iii) the saturated surface charge resulting from the avalanche. The experimental results were interpreted by computer simulation in terms of the model and were found to be in close agreement with the predictions.