Time evolution of the activation energy and volumes in electrical aging and wave packets in PE

Abstract

In the proposed model, one broken C-C bond is surrounded by a volume ΔV of stressed molecules and by a volume δv of strained molecules. These volumes could be depicted as the volumes in which the deformed molecules relax following the disturbance associated with the bond breaking. Both parameters are decreasing exponentially with time under constant field application. However, the time scales for the bonds breaking and for the molecular relaxations are not the same. When the energy barrier is calculated as a function of time for different fields and sample size, it appears that it is oscillating with time. Interestingly, the frequency of the oscillations is identical to the oscillations of wave packets observed in space charge measurements under the same experimental conditions. The influence of all contributing parameters is discussed and it is concluded that oscillations exist under all fields above the critical (threshold) field but at low fields, the time of appearance of the first one could be so long that it has never been recorded. The significance and implications of this phenomenon are briefly discussed.