Flexible Niobium-Tin Cables Suitable to React-then-Wind Approach to Fabricating Accelerator Magnets

60269 The long term goals for high energy physics research require Nb3Sn superconducting magnets with unprecedented performance and cost reductions for the construction of next generation particle accelerators. In this project, an innovative route will be used to fabricate flexible Nb3Sn cables that in turn could be used to fabricate Nb3Sn magnets by the more reliable and economical react-then-wind approach. In Phase I, a gas mixing setup, using an oxygen analysis unit in conjunction with a programmable furnace, was designed and commissioned. The system uses a computer data acquisition unit to continuously monitor the oxygen level during the heat treatment of Nb3Sn cables. The feasibility of producing flexible Nb3Sn cables by controlling oxide layer thickness was demonstrated, and between-wire bonding within sample cables was studied. Phase II will continue to exploit the advantages of oxide-control in fabricating flexible Nb3Sn cables, scale-up for intermediate scale productions, adapt the approach to use high performance internal tin Nb3Sn wires, conduct transconductance and stability measurements, and fabricate and characterize high current flexible Nb3Sn cables. Commercial Applications and Other Benefits as described by the awardee: The flexible Nb3Sn cables should find application in next generation particle accelerators, energy storage, fusion reactors, and NMR magnets.