Surface and interface physical phenomena induced by flashover across solid dielectrics in vacuum

Essentially surface flashover across a solid in vacuum is considered as a kind of complicated surface and interface physical phenomena. Based on the concurrent electrical and optical measurements and microscopic observations, the research works of our group concentrate on the relationship between flashover and surface/interface condition of insulating materials. There are some different optical phenomena detected from the surface of alumina and polymers, and we attribute the preflashover phenomena to the differences between the surfaces of different insulating materials and different electrode contacts. The experimental results reveal that, under low electric field, prior to field electron emission from the cathode triple junction, electroluminescence phenomena occur due to the radiative recombination of electrons and holes injected into the surface states from the electrodes. According to the results, the phenomena mentioned above are related to the surface states in the surface layer of a material. This work is a contribution to the traditional secondary electron emission avalanche (SEEA) model.