Influence of Axial Strain and Transverse Compressive Load on Critical Current of Nb₃Sn Wires for the FCC

Nb3Sn superconducting wires are under consideration for producing high field accelerator magnets for the proposed Future Circular Collider (FCC) due to their high critical field. R&D studies are ongoing worldwide with a target non-Cu critical current density (Jc) of 1500 A/mm2 at 4.2 K, 16 T. As an accomplishment of this R&D, one of the conductor manufacturers, JASTEC, has developed Nb3Sn wires with non-Cu Jc higher than 1100 A/mm2 at 16 T, 4.2 K by a distributed-tin (DT) method. In high field Nb3Sn magnets, degradation of performance has been frequently reported due to the brittleness of Nb3Sn and the high electromagnetic force. To realize more robust Nb3Sn accelerator magnets, electro-mechanical properties of the conductors should be deeply understood. In this study, the variation of the critical current with mechanical loading is evaluated for a DT Nb3Sn wire in two configurations, i.e., under axial strain and under transverse compression.