Development of a Novel Soldered-Stacked-Square (3S) HTS Wire Using 2G Narrow Tapes With 1 mm Width
Based on the pre-existing assembled, stacked, or twisted structures of high temperature superconducting (HTS) wires, a novel soldered-stacked-square (3S) HTS wire is suggested and developed through narrowing, stacking, and soldering processes in this study. For the fabrication processes of the 3S wire, a narrow 2G tape with 1 mm width is applied, and the stacking and soldering processes are completed simultaneously. To confirm the performance of the 3S HTS wire, several 3S samples are fabricated. For the 3S HTS samples, we evaluate typical electrical and mechanical properties, and investigated for the feasibility of the 3S HTS wire in the HTS applications. The test results show that measured critical currents of two 3S wire samples are 170 and 255 A, and their curves are typical ones of HTS tapes. The measured self-field ac loss is also reasonable, which is analyzed from both theoretical models of the elliptical and thin strip equations. Moreover, the minimum bending diameter for the 3S samples is approximately 60 mm, and the allowable axial tensile force is 350 N. These mechanical properties of 3S wire are satisfied for the HTS applications significantly. Finally, the smallest round structure of the HTS wire is conceptually suggested for the 3S HTS wire.