Charge packets modeling in insulating polymers based on transport description

Abstract

Charge packets in insulating polymers -especially in polyethylene, have been reported by many groups in different laboratories within the last 15 years. They constitute an unexpected behavior in charge transport and understanding the mechanisms for their formation and propagation could participate in deepening our knowledge of this class of material. Here, we concentrate on "slow packets" modeling. We first recall the general features of the experiments reporting charge packets and the models that have been proposed so far. We then use bipolar transport models featuring injection and transport in an attempt to approach the experimental behavior. The modeling allows discussing the physical situation for packets formation and propagation.

Space Charge Accumulation at Material Interfaces in HVDC Cable Insulation Part I—Experimental Study and Charge Injection Hypothesis

“…For the smooth backside and remolded surfaces, no impact on injection rate is predicted below 100 kV/mm and could therefore be used as references. The tunneling behavior occurring at low field levels with rough surfaces as compared to smoother surfaces, can additionally give rise to charge packets in the material [12].…”

Charge dynamics and its energetic features in polymeric materials

“…These results, although very preliminary, are further discussed in [42]. In particular, the model has also to approach the low field behavior for the same transport parameters which has not been considered here in detail.…”

“…the propagating packet and the accumulation of heterocharge near the cathode, but not the repetitive character of the propagation (a steady state is reached at 3000 s in the simulation). Moreover, by analyzing the dynamics of positive and negative carrier distribution as extracted from the simulation, it was evident that none of the elementary charge distributions had a packet-like structure (see [42] for further details). The positive packet evidenced in Figure 11 is therefore the result of an unbalanced dynamic situation in the density of positive and negative charges at any location, which has a packet-like structure for this particular combination of transport parameters.…”

Charge dynamics in polymeric materials and its relation to electrical ageing

“…In the framework of the model, bipolar transport provides the conditions for packet generation through field enhancement at the anode and also the conditions for packet disappearance when the charge distribution under steady state stabilizes the anode field above the lowest switching field (115 kV/mm). These results, although very preliminary, are further discussed in [41]. In particular, the model has also to approach the low field behavior for the same transport parameters which has not been considered here in detail.…”

“…the propagating packet and the accumulation of heterocharge near the cathode, but not the repetitive character of the propagation (a steady state is reached at 3000 s in the simulation). Moreover, by analyzing the dynamics of positive and negative carrier distribution as extracted from the simulation, it was evident that none of the elementary charge distributions had a packet-like structure (see [41] for further details). The positive packet evidenced in Fig.…”