Prebreakdown Electron Emission

Recent evidence suggests that the prebreakdown currents that flow between vacuum-insulated high voltage electrodes frequently originate from a non-metallic emission mechanism which is thought to be assocaited with some form of insulating/ semiconducting surface oxide or impurity concentration. This paper develops this theme by giving a brief review of the growing body of experimental evidence that can be cited in support of the above contention, a summary of the recent findings of on-going experimental investigations into this new emission mechanism, a discussion of possible new physical models and, finally, an assessment of our present understanding of prebreakdown electron emission and the technological implications.