THE TRANSVERSE STRESS EFFECT ON THE CRITICAL CURRENT OF JELLY-ROLL MULTIFILAMENTARY NB3AL WIRES

Experiments were conducted to determine the effect of transverse compressive stress (TCS) on the critical current of jelly-roll multifilamentary Nb3A1 wire (0.8-mm dia.) for magnetic flux densities up to 12 T. For comparison, identical experiments were performed for bronze-process Ti-alloyed multifilamentary Nb3Sn wire (1.0-mm dia.). Although the unstressed critical current density of Nb3Al was inferior to that of (NbTi)3Sn at high fields, under applied TCS Nb3Al exhibited less critical current degradation than (NbTi)3Sn. For example, at 12 T and 150 MPa, TCS-induced critical current degradation was approximately 20% for Nb3Al, whereas it was approximately 65% for (NbTi)3Sn. There is optimism that Nb3Al will evolve into a useful superconductor for large-scale, high-field applications.