Anomalous phenomena in solid dielectrics under high electric fields

Solid dielectrics have been used extensively in electrical and electronic industries. In the power industry, ultra high voltage transmission and cost saving of power equipment often result in that the dielectrics are operating under high electric fields. On the other hand, reduction in size for modern electronic systems also requires that the dielectrics operate reliably under high electric fields. It is therefore imperative to understand the response of dielectric materials to the high electric fields. In addition to high conduction current, power loss and potential breakdown, it has been observed over the years there are several anomalous phenomena occurred under high electric fields. These are surface potential cross-over phenomenon in corona charged dielectrics, discharging current flowing in the same direction as charging current, space charge fast decaying and transient space charge limited current. In the present paper all these phenomena have been experimentally demonstrated but most importantly a bipolar charge injection model has been used to understand the observed phenomena under high dc fields. Preliminary simulations based the model reveal that the presence of bipolar charges is the key to explain these anomalous phenomena.