Investigation of Soldered REBCO Tape–Copper Joints for Superconducting Applications

Abstract

In the growing field of high-temperature superconductor (HTS) applications, soldered tape-copper joints are of significant importance. This is because the resistance of the joint often plays a decisive role in the design of a superconducting device, such as current leads or current terminations of cables. A common requirement to the joint is as-low-as-possible resistance and reliable reproducibility, which is crucial for achieving a homogeneous current distribution being independent within each HTS tape placed in a superconducting device. From previous studies, it is known that resistance of HTS tape-copper joint can vary for different tapes and solders. This resistance can be considered as a sum of several contributions: REBCO-layer-copper-laminating-layer interface resistance in HTS tape, copper-laminating-layer-solder and solder-copper interface resistances, and solder and copper resistances. Here, we present current status of investigations on tape-copper joints and trials to estimate different contributions in their resistance value.