Self-controlled pre-breakdown discharges in planar symmetry |
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Authors: | Altafim RAC Ferreira GFL Giacometti JA |
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Affiliation: | Inst. de Fisica de Sao Carlos, Sao Paulo Univ. ; |
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Abstract: | In measurements on Teflon FEP films charged in ⩽50 μm air gaps by microsecond impulse voltages, a uniform charge deposition on the films was observed. A regular increase of the film surface potential from a threshold value of the peak impulse voltage was found. However, for 300 μm air gap it was observed that abrupt charging occurs at a lower threshold voltage, indicating breakdown, and the charge deposition on the film becomes nonuniform. The behavior in air gaps <50 μm is explained here using Townsend's theory of pre-discharges. It is shown how and why the interposed insulating film acts to make the system self-controlled, thus avoiding breakdown in the air gap, despite the large values of the applied peak impulse voltage |
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