MODEL FOR THE LOW-TEMPERATURE TRANSPORT OF BI-BASED HIGH-TEMPERATURE SUPERCONDUCTING TAPES

A grain-structure model is used to obtain the low-temperature transport properties of polycrystalline Bi-based high-temperature superconducting tapes, including the magnetic-field-dependent critical current. The grain structure is regarded as resembling a brick wall, such that the net horizontal super-current passes from brick to brick chiefly through the horizontal junctions between bricks. A high-field critical-current plateau is predicted, assuming inhomogeneous Josephson junctions between highly anisotropic superconducting grains.