Numerical study of space charge dispersive transport in non-polar electrets

The space-charge dispersive transport in non-polar electrets is studied numerically and experimentally. The dynamics are investigated through continuous-time random walks by Monte Carlo simulation. The stepping-time density of Montroll (ψ(t)∝t^-1-α) is applied for computation. By keeping the temperature at each stepping interval, charge transport under isothermal conditions is studied to simulate the real charge decay process in non-polar electrets aged at fixed temperatures. Experiments on polypropylene film electrets were carried out for comparison. Samples were constant-voltage corona charged at RT for 10 minutes and then aged at various selected temperatures for given time periods. The mean charge depth was measured for comparison to numerical results by means of heat pulse technique. Experimental results of other non-polar electrets are also given to support our model