Ultra-Violet Induced Insulator Flashover as a Function of Material Properties
AIR FORCE WEAPONS LAB KIRTLAND AFB NM
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Previous work has shown that a small fluence of UV photons is sufficient to initiate flashover at the insulatorvacuum interface of a vacuum insulated transmission line. 1 In this paper we examine the behavior of polyethylene, polystyrene, and teflon insulators in which the dielectricvacuum interface was oriented at a 45-degree angle to the applied electric field. Field stress was varied over the range 10-70 kVcm, both positive and negative polarity. The insulators were exposed to various UV spectra with photon energy up to 12 eV. All insulator materials were unaffected by radiation with photon energy 3 eV or less regardless of power, The geometry which withstood the greatest photon fluence was, for every material, the inverse of the geometry suggested as preferable by applying conventional DC breakdown criteria. A model explaining the polarity phenomena as well as the insulators behavior under various spectra is proposed.
- Electricity and Magnetism