Modelling the effects of space charge distributions on TSDC spectra

The technique of thermally stimulated discharge current measurement (TSDC) has been widely used to determine the properties of dipolar relaxations in materials or the depths of charge storing traps within a polymer. Measurements of the changes in these properties as a function of ageing has also provided insights into the underlying degradation mechanisms. To produce a TSDC spectra a sample is taken through the following series of procedures. The sample temperature is raised and a polarisation field is applied through an appropriate electrode system. After a suitable time period to allow the polarisation processes to take place, its temperature is lowered while the polarisation field is maintained. The electrodes are then shorted through an electrometer and the sample temperature is raised linearly. As the temperature is increased current peaks may be observed as different components ofthe polarisation within the sample relax, By analysing the shape and position of the peaks it should be possible to determine the activation energies and pre-exponential factors for the relaxation processes. A modelling method to examine these processes is described