An Internal Tin Tube Process for High Performance Nb3Sn Conductors

73080S03-I The high energy physics (HEP) community requires the development of superconducting wires for use in magnets generating magnetic fields of 15 tesla and above. Currently, Nb3Sn is the only commercially available superconductor capable of operating at such high fields. However, its performance to date does not meet the stated requirements of the HEP magnet community. This project seeks to demonstrate a new process to improve the critical current density. A niobium tube will be filled with tin rods and processed into a multifilamentary array. This new process differs from past tubular niobium projects by using very-high-tin-content cores, and minimizing the amount of copper in the filament. The critical current density will be increased by maximizing the components that lead to the largest quantity of superconducting compounds, while minimizing any component that does not contribute to the current-carrying capacity. Phase I will produce copper clad niobium tubes with an outer tantalum barrier. These tubes will be filled with three tin rods of varying diameter in order to explore the minimum quantity of copper that is necessary to react the tin and niobium to form superconducting compounds. Multifilament conductors will be produced by conventional restacking and cold-drawing processes. Superconducting electrical properties will be measured at 4.2K and in magnetic fields up to 14 tesla. Commercial Applications and Other Benefits as described by awardee: High performance, multifilamentary Nb3Sn should find application in high energy physics particle accelerators and magnetic confinement fusion machines. Commercially, such conductors should find application in high frequency NMR magnets by taking advantage of the higher critical current density in order to reduce the size and overall cost of the magnet system.