Research and development on surface flashover voltage of ceramics

Alumina ceramics is one of the most important and widely used materials for hermetically sealed high voltage insulators. However, their ability to withstand high voltage is limited by the surface flashover resistance of the ceramic material. Despite extensive research to improve surface flashover voltage in a vacuum, the surface flashover resistance mechanism is not well understood. It is hypothesized that surface flashover depends on the material properties of the ceramics. In this paper, we will report our studies regarding surface flashover of various types of alumina ceramics in which resistivity and secondary electron emission coefficient differs in an ultra-high vacuum atmosphere. We found that it is possible to control surface flashover by lowering resistivity and the secondary electron emission coefficient of the ceramic material. (author)