Space Charge Research on Epoxy Resin Under Low Temperature and Large Thermal Gradient

The study of space charge characteristics of insulating materials under large thermal gradients is of great significance for the design of superconductive pipelines. In this work, we improve the pulsed electro-acoustic system to research the space charge characteristics of epoxy resin under a great thermal gradient of $- 150 ^{\circ}\text{C} \sim 20 ^{\circ}\text{C}$. The removal of the impact by thermal gradient is completed by interpolation method using a theoretical approximation. At various voltages and different polarities, the polarization and depolarization processes reveal the low injection of electrodes and the low mobility of carriers at low temperatures. The comparison of space charge results between room temperature and thermal gradient shows that a large number of bipolar carriers may be hidden in the sample at room temperature.