Negative space charge and electric field intensity in polymeric insulators at low temperatures |
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Authors: | V A Zakrevski? N T Sudar’ |
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Institution: | (1) A. I. Ioffe Physicotechnical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia |
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Abstract: | The effect of negative space charge accumulation due to injection of electrons from cathode microprotrusions on the steady-state
and transient electric field distributions in polymer dielectrics is discussed. An isolated microprotrusion is modeled by
a spherical capacitor in which an electrode of smaller radius is the cathode. The calculations include the fact that the distribution
of negative space charge depends on the rate of capture and liberation of electrons by traps, while the activation energy
of this process depends on the electric field intensity. An exponential energy distribution is proposed for the traps. It
is shown that significant electrical overvoltages can only appear near the cathode microtips immediately after switching on
the voltage. In the course of 10−6–10−5 s, the coefficient of electrical overvoltage drops to a few units and approaches its steady-state value. The region of significant
electrical overvoltage is localized, and is the same order as the dimensions of the microtip.
Fiz. Tverd. Tela (St. Petersburg) 40, 1167–1172 (June 1998) |
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