Changes of space charge profiles in PET electrets after thermally stimulated discharges

Behaviour of electric changes in the PET film has been investigated under the condition of partial discharging at higher annealing temperatures. The PET electrets corona-charged at room temperature and 440 K were investigated. The step electro-acoustic method was used for the measurement of space-charge distributions. The highest surface charge densities were obtained after negative corona charging at 440 K