Verification of role of prebreakdown phenomena in the development of flashover in vacuum

The paper presents results of numerous experiments which have enable verification of the role of prebreakdown phenomena in the mechanism of flashover in a vacuum. In many papers, authors stress a very considerable role of field electron emission in the development of flashover, the mechanism of secondary electron emission, as well as the effect of generating the surface charge on the dielectric material. In the authors´ opinion, in real insulating systems, the occurrence of field electron emission is very limited. In all cases of vacuum spacers, whose height is greater than 10 mm, the development of flashover depends only on microdischarges. A strong relationship between the electric strength of vacuum spacers and the parameters describing microdischarges is observed