Effects of UV illumination on surface flashover under pulsed unipolar excitation

Undesired surface flashover of high voltage support structure can severely limit the compactness of open air high voltage systems. Only recently, increased effort has been invested in characterizing and quantifying the physical processes involved in surface flashover occurring under atmospheric conditions and under the influence of UV illumination. Presently, UV flash lamps as well as a solid-state UV source, for their much faster turn-off times, are utilized in conjunction with a high temporal resolution testing apparatus. The UV pulse, voltage, current and flashover self luminosity will be measured with high temporal precision. A simple model that describes the observed behavior as well as a more advanced analysis utilizing a Monte Carlo type code for the electron collision dynamics will be presented.