Description of bipolar charge transport in polyethylene using a fluid model with a constant mobility: model prediction

TLDR

Charge transport and storage in disordered media, particularly low‑density polyethylene, require models that capture bipolar conduction and space‑charge effects, and several existing approaches have been reviewed. The authors develop a conduction model to describe bipolar transport and space‑charge phenomena in low‑density polyethylene under direct‑current stress. The model adopts a fluid‑type description with constant carrier mobility, incorporates key assumptions, and simulates external current, trapped and free charge, electric field, and recombination under constant, stepped, and polarization–depolarization voltage protocols. Simulation results show that the model reproduces the characteristic external current, electroluminescence, and charge‑distribution patterns observed experimentally in polyethylene.

Abstract

We present a conduction model aimed at describing bipolar transport and space charge phenomena in low density polyethylene under dc stress. In the first part we recall the basic requirements for the description of charge transport and charge storage in disordered media with emphasis on the case of polyethylene. A quick review of available conduction models is presented and our approach is compared with these models. Then, the bases of the model are described and related assumptions are discussed. Finally, results on external current, trapped and free space charge distributions, field distribution and recombination rate are presented and discussed, considering a constant dc voltage, a step-increase of the voltage, and a polarization–depolarization protocol for the applied voltage. It is shown that the model is able to describe the general features reported for external current, electroluminescence and charge distribution in polyethylene.