Application of TSD and SEA methods for measurements of space charge and polarisation in PET electrets

The step electroacoustic (SEA) and thermally stimulated discharge (TSD) methods were applied for analysis of electric state in corona charged samples. Simultaneous measurements of electric field distribution and current during thermally stimulated discharge allow to get information on real space charge density and quasi-frozen polarisation in a dielectric. The TSD and SEA measurements are useful tools to determine the local values of real and polarisation charges in PET electrets and their decay during thermally stimulated discharging. The TSD current in PET electrets origins from decay of average value of quasi-frozen polarisation.