Relationship between space charge behavior and trap energy density distribution: A simultaneous measurement

This paper gives a detailed introduction of a simultaneous measurement system that can obtain the space charge distribution and the thermally stimulated current (TSC) of the same sample over the temperature range 213–373 K. This measurement system adopts a 4-electrode structure and a time sharing strategy to avoid the mutual interference between the space charge measurement and the current measurement. In addition, a space charge recovery method is proposed to obtain the real space charge distribution from the original data under varying temperature situation. Furthermore, a simultaneous measurement is performed on a cross-linked polyethylene (XLPE) sample. The experimental results show that the positive charges accumulate and dominate in the bulk during polarization and the cooling stages. During the thermal stimulation stage, the accumulated charges decay after ∼330 K, and the thermally stimulated current increases significantly after ∼330 K. The analysis results imply that the release of trapped charges may be the main cause of the thermally stimulated current, and most of the charges are trapped in traps more than 1 eV.