Development of Joints Between Two Parallel SS-Laminated BSCCO/Ag HTS Tapes

Stainless-steel (SS)-laminated high-strength high-temperature superconductor (HTS) BSCCO tapes are now commercially available for different practical applications. These SS-laminated HTS tapes are tolerant to smaller winding diameters, and the pancake winding becomes much easier due to higher tensile strength. However, the joining of two parallel SS-laminated HTS tapes is more complicated because of their limitation in maximum temperature exposure. The joining between the pancakes however becomes resistive due to the SS-laminated layer. We have experimentally studied the performance of the bridge joint between two parallel SS-laminated BSCCO tapes with different numbers of cross bridges of two different types of BSCCO tape. The splices of both SS-laminated BSCCO tape and silver (Ag)-sheathed BSCCO tape have been used as cross bridges at the joint. The current–voltage $I$–$V$ characteristic curves of the joints were investigated at 77 K, which is liquid nitrogen temperature. Joint resistance has been estimated from the $I$– $V$ characteristic curve. The lowest joint resistance achieved at 77 K at self-field, with six bridges made of SS-laminated HTS tape, is 0.78 $mu Omega$, and the lowest joint resistance of six Ag-sheathed HTS bridges is 0.54 $muOmega$. The corresponding contact resistances are 0.402 and 0.27 $muOmegacdothbox{cm}^{2}$ for both types of joints.