This project aims to identify the insulator surface properties, at the microscopic level, that control the electron multiplication process leading to surface breakdown under electric excitation. The surface properties of single crystal (defect free) and polycrystalline alumina (99.9% Al2O3) will be systematically altered by mechanical, thermal, and chemical treatments. Different treatments are intended to modify, in a deliberate and controlled manner, such surface physical and chemical properties as a microdamage, residual stress, surface dielectric constant, oxidation state, surface potential, and density of localized (defect) levels in the band gap. Phase I consists of three subsections: (a) Mechanical treatment, (b) Thermal treatment, and (c) Surface annealing. Phase II will consist of (d) Chemical treatment, and (e) Surface cleaning. %%%% This project is a comprehensive study of high voltage flashover phenomena, which have high merits in scientific contents. The planned materials variables are based on preliminary work, and can be expected to yield significant results. The results can be useful to the electrical equipment and electronic industries. They should extend the understanding of surface discharge processes, not only for vacuum gaps but also for general gas insulation problems.
