Local electrical overstressing in polymer dielectrics

Using a spherical concentric capacitor as a microspike model, the electric field distribution in a polymer dielectric material with shallow and deep electron traps is investigated. It is established that in the course of field emission from microspikes on the electrode and space charge accumulation on the traps, the values of coefficient of electric overstresses depend on temperature, injection barrier height, and trap concentration and depth in the polymer material. The behavior of this coefficient is characterized as a function of the mean field strength.