Low Temperature and Magnetic Field Performance of Spliced Commercial YBCO CC

The design of next-generation magnets based on 2G high-temperature superconductors requires a careful investigation of the possibilities and performance of joints between different superconducting wire pieces. In this paper, we present a study of the electrical performance of splices made with commercial Superpower ReBCO tapes at both 77 K and 4.2 K. For this study we developed a special splicing device based on the hot-bar soldering technique that allowed estimating the degree of reproducibility of the splicing method in view of future standard series production. During our study we investigated the influence of the splicing parameters (temperature, pressure, duration, flux fluid, solder composition, cooling etc.) on the final joint performance in terms of specific resistance, critical current degradation and n-value degradation. The best performing splice was characterized at 4.2 K in perpendicular magnetic field up to 11 T. The results show an excellent degree of reproducibility with no appreciable degradation of the original tape performances. The ultimate splice resistance seems determined by the intrinsic architecture of the tape rather than by the splicing method itself.