Measurements on Critical Current and Bending Strain Tolerance for Ex Situ ${{\rm MgB}_{2}}$ Wires and Tapes Under High Field up to 8 T

Abstract

The critical currents of several configurations of ${{\rm MgB}_{2}}$ conductors from Columbus Superconductors SpA were characterized under high magnetic fields. The measurements were performed at LNCMI Grenoble at a temperature of 4.2 K and under a magnetic field ranging from 3 up to 8 T. The characterization of the different configurations takes into account different parameters, such as the filling factor, number of filaments, shape, and type of matrix. Moreover, in order to define the minimum bending radius, the different samples were prebent at room temperature on different diameters (from 50 to 400 mm) and then straightened again before being tested. This work investigates the critical current density $J_c$ , engineering current density $J_e$ , and the influence of bending strain over the critical current. The different samples are compared according to their critical current densities, engineering densities, and bending strain tolerances.