Study on space charge dynamics by computer simulation: Formation and transport of space charge packet

A packet-like space-charge behaviour in the oxidized cross-linked polyethylene (XLPE) films doped with an antioxidant was discussed by computer simulation. The model is based on the following assumptions, i.e., (1) both electrons and holes are injected from the electrodes and they migrate to the opposite electrodes by hopping transport, (2) holes are also supplied from acceptor sites depending on the field, (3) a hole can be excited to the hopping level only via the intermediate level (trap level). In this model, a space-charge packet is not caused by the excess of mobile electrons but by the deficiency in mobile holes. Ionized accepters left behind by hole migration form an apparent charge-packet and it propagates towards the anode as the high field region moves