Microscopic models for ageing in solid dielectrics

A review is presented of the theoretical concepts and experimental techniques for understanding aging in solid dielectrics. No cumulative aging effects are detected at fields smaller than the threshold field for high mobility transport. If this field is exceeded in the vicinity of a defect then materials degradation can be observed by various techniques. In the final phase of this degradation there is observed the onset of femto-discharges, which after some incubation period lead to picodischarges and the initiation of an electrical tree