Dielectric characteristic of insulating paper - Ice composite material in liquid nitrogen

Paper-liquid nitrogen (LN₂) composite system has been used as one of the insulating systems of the high-temperature superconducting cable. In this system, partial discharge may occur inside the N₂ gas bubbles due to the gasification of LN₂ in the paper. We have been suggesting the paper-ice composite material as one of the candidates for the insulating system with LN₂ in high-temperature superconducting cables. The paper-ice composite material is an insulating paper filled with ice and it could inhibit the partial discharge inside the microscopic N₂ gas bubbles remained in the paper. This research investigated capacitance and dielectric loss tangent of the paper-ice composite material with changing field strength. Finally, we clarified that the paper-ice composite material could provide lower capacitance system to paper-LN₂ composite insulating system for high temperature superconducting cables.