Surface flashover characteristics of polished-polycrystalline diamond and diamond-like carbon (DLC) thin films in vacuum

Polycrystalline diamond and diamond-like carbon (DLC) thin films are becoming attractive candidates for protective coatings, and, as dielectric materials. They may also find application areas in construction of spacecraft components. However, the space environment is very harsh, and survivability of these materials in that environment has not been clearly understood. In this work, the authors present experimental results identifying some surface flashover characteristics of polycrystalline diamond and diamond-like carbon (DLC) thin films in space vacuum conditions. The polycrystalline diamond and DLC samples used in the experiments are produced by a microwave plasma deposition technique. The diamond films were polished to optical-quality before the experiments. The electrode material was copper, and a dc voltage was applied between the electrodes. When surface flashover occurred between the electrodes, it only occurred on the surface of the diamond or DLC samples. Surface flashover voltage characteristics and breakdown voltage-wave forms of polished polycrystalline diamond and DLC thin film samples were determined