Measurement of AC insulation losses at cryogenic temperatures

The design of superconducting transmission cables requires a systems approach which includes consideration of the conductor, insulator, cryogenic envelope and refrigerator. Each component of the system must function satisfactorily without disrupting the other system elements. The cable insulation must meet demanding requirements of breakdown strength, corona inception level and mechanical integrity. But it must accomplish all this without burdening the refrigerator with a heat load due to ac dielectric losses.