Magnetic field dependence of the critical current in MgB2 and Bi-2223 superconducting tapes fabricated by the powder-in-tube method

摘要

The transport properties of powder-in-tube processed superconducting tapes based on the Bi-2223 and MgB2 compounds were measured at liquid helium temperature as a function of the magnetic field amplitude and orientation with respect to the conductors. Critical current measurements on short samples were performed in a magnetic field up to 20 T. From this data, we found that commercial multifilamentary Bi-2223 tapes, in spite of the well-established processing route, show some differences over a standard common trend, if manufactured by different suppliers. Nevertheless they all carried remarkable transport currents up to the highest magnetic field of measurement. The transport properties of MgB2 tapes presented very different features depending on the thermo-mechanical treatment they were subjected to during the fabrication process. A small critical current was measured at a field as high as 16 T on a multifilamentary MgB2 tape. In the magnetic field domain below 1 T, MgB2 tapes carried critical currents in excess of 1000 A at a critical current density of greater than 4·105 A/cm2.