Influence of Cabling on Current Characteristics of Round MgB2 Wires With Different Design

MgB2 superconductors are currently considered as a prospective for different applications, in particular for use in high-current super-conducting electrical power lines. The MgB2 superconductors are rather sensitive to the strain that unavoidably occur during a cabling process, that is why a standard cabling machine should be adapted for minimization of strain before fabrication of cables based on MgB2 wires. We performed the comparative study of critical current gradation of two round ex situ MgB2 wires during the fabrication the model 18-strand cable. Both wires were produced by the Columbus superconductor and differ by mechanical properties, matrix composition, and initial critical current. Our cabling machine was previously modified for minimization of strain on the base of calculations of strains dependencies on bending and twisting of MgB2 wires. Mechanical properties of MgB2 wires were analyzed as well. The changes of critical currents of both wires during the 18-strand cable fabrication and insulation were measured. The results of calculations, critical currents tests, and mechanical properties are presented and discussed.