Estimation of flashover voltage along cylindrical insulator in vacuum

This paper deals with a method to estimate the surface flashover voltage of an insulator in vacuum, in which the distribution of surface charge due to the Secondary Electron Emission Avalanche (SEEA) is taken into account. We show experimental and calculated results for cylindrical insulators made of glass ranging up to 50 mm in length. Since surface roughness of specimens affects the SEEA charge density, its influence on the flashover voltage is also examined. The calculation and experimental results have shown good agreement. For further confirmation of the applicability of our method, we have examined the flashover characteristic of a specimen when its surface consists of smooth and rough regions.