Shape anisotropy in critical current densities of Nb3Sn tapes produced by the bronze process

A systematic study of the shape anisotropy in critical current densities of bronze processed Nb3Sn tapes was made. [Critical current densities of the Nb3Sn tapes are greater when applied magnetic field H is perpendicular, Jc( ), to the flat face of the tape than when it is parallel, Jc(∥), to the face while current is perpendicular to H in both cases.] In these tapes, the anisotropy is not only due to the shape (columnar or equiaxed) of the Nb3Sn grains, but also in many cases, it is related to the similar anisotropy in the critical magnetic fields Hc2. However, the origin of this shape anisotropy in Hc2remains unknown.