A method for space charge study in dielectrics

Summary form only given, as follows. It is known that the conduction current through a dielectric material is related to space charge accumulation in the material. It is important to know the amount of charge stored in dielectric. Valuable information concerning charge stored in a dielectric material is obtained by using thermally stimulated discharge current method. We propose to use a variant of this method for space charge study as follows. An electric field is applied to the sample for a given time at a sufficiently high temperature so that the space charge formation process has an important role. Immediately after field removal the sample is not cooled down for polarization and space charge freezing. In contrast the sample is heated up and the released current is measured. Because the temperature is higher than forming temperature the measured current is determined by space charge existing in the sample; this method is known as thermally stimulated space charge current. The sample is heated at a temperature at which it is still mechanically stable. The experiment is continued at this temperature by measuring the isothermal final discharging current. When the measured current is in the parasitic limit it is considered that all the existing space charge in the dielectric has vanished. The relation between the total charge that flows through circuit during charging and the total charge liberated from the dielectric is analyzed.