Evaluation tests for large scale multi-filamentary Nb3Sn superconductors

Six different configurations for multifilamentary Nb3Sn conductors for large scale magnets with high magnetic fields were developed and tested. These conductors, which could carry approximately 1kA at 13T, were cryogenically stable, reinforced superconductors 4.5mm × 10mm in size. Critical currents, stability and the effects of stress were measured in short sample tests. Conductor stability was related to barrier configuration. At stresses above 250-800 MPa the critical current was significantly degraded, with the magnitude of the reduction depending on reinforcement techniques and the construction of the conductor. A monolithic conductor which was composed of filament groups surrounded by barriers, each of which was composed of 331 filaments, and which was about 30% stainless steel by total volume was found to be suitable for large scale magnets with high magnetic fields.