Simultaneous measurements of space charge distribution and external current

Space charge distribution and external current in low density polyethylene (LDPE) have been measured simultaneously using an improved PEA (pulsed electro-acoustic) measurement system. They are usually measured using different devices independently. However, to investigate the relationship between the space charge behavior and the conduction current, it is necessary to measure them simultaneously in the same sample. Therefore, we have developed an improved PEA system to measure them simultaneously. In this improved system, the space charge distribution and the external current measurements are carried out by switching connection of the lower electrode between electrometer and ground. As the result of simultaneous measurements, it is found that the external current increases during the injection and traveling of positive charge from the anode towards the cathode. To explain the phenomenon, we estimated displacement current, conduction current and conductivity distributions in the sample from the results of the measurements. Moreover, we examined the relationship between those distributions and charge behavior in LDPE.