Space charge packet behavior in low density polyethylene

In this paper, Pressure Wave Propagation (PWP) method was utilized to observe the space charges evolution in sheet sample of low density polyethylene (LDPE). The space charge packets are generated at the anode and move across the sample to the cathode regardless of the polarity of DC voltage. Along with the space charge packets to migrate into the depth of sample, the velocities and the amplitude of these packets are smaller. The mobility of space charge packets is in the order of 10^-14 m²/Vs at room temperature. An interesting phenomenon is that almost the same packet can be recreated in the used samples after several days under the same condition. The migration of space charge packets is discussed in the paper.