Effects of space charge on electrical conduction in high-density polyethylene

Direct probing of space charge was carried out on high-density polyethylene doped with antistatic agent using a thermal pulse method. Prominent positive space charge was found to be formed near the cathode by voltage application. The field at the cathode is enhanced by the space charge. The conduction can be quantitatively explained by Schottky-type electron injection under the enhanced cathode field. The anomalous discharge current after short-circuiting, which flows in the same direction as the charging current, can also be explained by the continued electron injection due to the remaining positive space charge.