Storage and decay of electrical charge in high temperature dielectrics

The results of research into charge storage and its decay are reported for aromatic polyamides which are high-temperature dielectrics. Both thermal poling and corona charging techniques are used. Thermal poling is also carried out at various electric fields and TSD (thermally stimulated discharge) currents are measured by varying several parameters, such as the heating rate, material thickness, and storage temperature. The activation energy for the release of charges is determined by the plots of current and reciprocal of the temperature. The TSD current shows a peak at 135 degrees for a rate of heating of 1 K/min and shifts to a higher value. The charge released to the external circuit is proportional to the poling field. The relaxation time for the delay of charges has been measured by a new experimental procedure, and it is concluded that the material shows dipolar relaxation at 135 degrees C. A positive corona discharge in a point plane gap in air at atmospheric pressure is used for corona poling.<>