Critical current density and best transport current of an Ag-sheathed Bi-2223 tape conductor

Abstract A critical current density of as high as 66,000 A/cm 2 has been achieved in an Ag-sheathed Bi-2223 superconductor. Also a coil wound with the same kind of wires has generated a magnetic field of 1.5 T. The conductors of this coil consisted of six elemental conductors connected in parallel. The reason why the parallel conductors were used was that it was difficult to fabricate a single conductor which had the capability of passing a large amount of current at a high critical current density. In an Ag-sheathed Bi-2223 superconductor, one limiting factor prevents a single conductor from having a large current-passing capability and the highest critical current density, at the same time. A larger amount of current passes through a conductor with a larger cross-section. However, we can only realize a higher critical current density with a conductor of a smaller cross-section. This core size limitation (CSL) gives rise to many problems that need to be solved when considering large scale applications in the electrical engineering field with Ag-sheathed Bi-2223 superconductors.