Charge transport properties of insulators revealed by surface potential decay experiment and bipolar charge transport model with genetic algorithm

To evaluate spacecraft charging level and predict surface and internal electrostatic discharging (ESD) probability, it is important to know the charge transport properties of high insulation materials, such as epoxy resin/glass composition (FR4), Teflon and polyimide. In present work, the charge transport properties of the space insulators are revealed by a bipolar charge transport (BCT) model combined with genetic algorithm (GA). It has been found that the BCT model can be used to simulate the experimental surface potential decay (SPD) results, and these two results are in good agreement with each other. The BCT model consists of charge injection, conduction, trapping, detrapping, and recombination processes. Stochastically initiating a series of charge transport parameters by GA, we can compute the SPD curves of materials by the BCT model. Used GA operates, the best fitting SPD curve of the experimental results can be obtained. From the comparison of the calculated and the experimental SPD results, we obtain the charge transport properties of FR4 and polytetrafluoroethylene (PTFE).