Observation of current spikes caused by possible fast carrier transport through a low-density polyethylene sheet under high DC fields

Abstract

The repetitive current spikes caused by possible fast carrier transport through a low-density polyethylene (LDPE) sheet under high DC fields from 0.1 to 2.0 MV/cm are simultaneously measured with space charge distributions. Although a constant dc voltage is applied to the sheet between a semi-conduction (SC) electrode and an Al-evaporated electrode, large current spikes of the order of 10−8 A are repeatedly superimposed onto the dc conduction current of the order of 10−10 A. Results of the space charge measurements indicate that the charge injection from the SC anode and the subsequent deep penetration into the LDPE bulk can be observed when the current spikes are repeatedly detected. In addition, we find that a phenolic antioxidant added into the LDPE has an inhibition effect not only on the space charge penetration but also on the repetitive current spikes. This finding suggests that the antioxidant additive produces a deep trapping site for fast-moving carriers.