Theoretical and Experimental Studies on 600 A-Class Current Leads of Copper and REBCO Wires Cooled With a Single Cryocooler

A 600 A-class cryogen-free current lead was developed using stranded copper and REBCO wires, and the feasibility of the design was confirmed. To suppress heat intrusion, the current leads were constructed using copper for the room-temperature section to the first stage of a GM cryocooler, and HTS wires for the section from the first stage to the second stage of the cryocooler. To investigate the impact of lead length on performance, three copper leads of varying lengths were fabricated. Subsequently, temperature sensors were attached to the copper leads, and the temperature distributions during current conduction were investigated in a test cryostat consisting of a single 4 K-GM cryocooler. As a result, continuous current conduction for over 1000 seconds was successfully achieved using optimally designed copper leads and HTS leads. The calculated and measured temperature distributions of the copper leads globally matched, demonstrating the validity of the design.