Development of a large current capacity conductor using Bi-system superconductors

We developed a new strong Rutherford cable using Bi 2 Sr 2 CaCu 2 O y (Bi-2212) high temperature superconducting (HTS) wire, which consisted of 427 superconducting filaments and AgMgSb alloy outer sheath. This wire exhibited excellent critical current (I c ) and critical current density (J c ) values at 4.2 K in self-field (285 A and 340000 A/cm 2 , respectively) and a room temperature tensile strength of 180 MPa. The Rutherford cable was prepared with a NiCr alloy strip as a cable core. The degradation of full cable I c induced by Ni diffusion was reduced by introducing a ceramic barrier layer between the Bi-2212 superconducting wires and the NiCr cable core. A full cable I c value of 3500 A at 4.2 K in self-field was obtained in short sample fabricated by using a cable core with a ZrO 2 film barrier layer. Finally, we fabricated an 80-m-long Rutherford cable by using a cable core with a MgO tape as a barrier layer and evaluated its full cable I c . I c values of 17-m-long sections cut from a continuous 80-m-long cable were greater than 2700 A at 4.2 K in self-field.