Critical Current Enhancement of BSCCO Tapes in Stacked Conductors With Ferromagnetic Sheets

A 200-m-long high-temperature superconducting (HTS) cable for dc power transmission, called CASER-II, was constructed at Chubu University using BSCCO tapes in 2010. The critical current of HTS tapes has been extensively studied against their layouts to improve the performance of HTS tapes in the cable. The multilayer structure of the tapes is needed to obtain a high current capacity. In the stacked tape conductors, the critical current of BSCCO tapes shows strong dependence on the current feeding directions between the tapes. The critical current is improved when the opposite-direction current is applied to them and reduced for the same-direction current feeding mode because of the strong magnetic field interaction between them. By using the ferromagnetic sheets, self-field of HTS tapes will be affected and may improve their critical currents. This technical paper presents the measurements of the critical currents of BSCCO tapes in the stacked conductors covered with the ferromagnetic sheets under different current feeding modes. We will present effects on the critical current of HTS tapes of the magnetic field from the currents applied to the neighboring tapes and the ferromagnetic sheets through the magnetic field analysis.