The effect of charge recombination on surface potential decay crossover characteristics of LDPE

Bipolar charge injection and transport has been observed in corona charged low density polyethylene (LDPE) during surface potential decay (SPD) processes. The proposed bipolar charge transport (BCT) model can well interpret the SPD characteristics, especially the SPD crossover phenomenon. Bipolar charge transport in materials can result in charge recombination (CR). It is evident that CR can affect space charge distributions and external current of insulators subjected to electrical stresses. Therefore, it is of interest to investigate the influence of CR on the SPD and crossover behaviors of charged insulating materials. We deal with the SPD properties of corona charged LDPE by the BCT model with a constant charge carrier mobility, including charge trapping/detrapping and CR. The non-linear charge advection-reaction equation in the BCT model is solved by a highly stable and accurate finite difference weighted essentially non-oscillatory (WENO) method with the Strang splitting method. The Poisson's equation is resolved by boundary element method (BEM). The simulation outputs show that the recombination coefficients can affect the space charge and electric field profiles, and recombination rate in the corona charged material. We find that the larger the recombination coefficients are, the higher the threshold initial surface potential for SPD crossover will be.