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Numerical analysis of various space charge packet behaviors in low-density polyethylene under different high DC voltage

The generation and migration of space charge packets in low-density polyethylene (LDPE) materials have been investigated in recent papers. A large number of measuring results indicate that space charge behavior show great difference in the course of formation and movement due to the difference of applied field and material characteristic. This gives difficulties to study the feature of packet-like charge behavior in LDPE. In order to give a reasonable explanation for various kinds of packet-like charge behaviors, a simple numerical simulation is proposed which is based on the analysis of experimental results. The model is considered the influence of the electrode injection and carrier velocity as well as trap level caused by the electric field distortion. Based on the idea that the hole mobility will be expected to decrease as the increasing field causes more disorganization of polyethylene chains, we give a hypothesis that a negative differential mobility curve could be utilized to describe the relation between the migration velocity and electric field. By considering such a model, we simulated various kinds of packet-like charge behaviors and the results of simulation show a good agreement with the experimental results from different groups.