A Novel Low-Cost Nb3Sn Strand with Distributed Tin Alloy Sources for Fusion Applications

In order to successfully sustain a fusion reaction, peak magnetic fields on the order of 12-13 Tesla will be required. This can only be accomplished by advanced superconductors such as Nb3Sn. However, further improvement in the cost-performance of the Nb3Sn conductor and scale-up of manufacture will be needed to ensure the overall economic success of the fusion machine. This project will develop a low-cost, distributed-tin manufacturing process to meet the need for large-scale conductor production. The approach involves the development and demonstration of a substantially higher non-Cu critical current density. In Phase I: (1) a new Sn alloy with second element addition will be developed to significantly enhance flux pinning properties; (2) a Cu/Nb7.5Ta composite will be extruded and drawn to restack size; (3) the composite will be assembled utilizing a novel conductor architecture, which will allow insertion of a new Sn alloy; (4) the new low-cost conductor will be processed and assembled; and (5) the billet will be drawn to final wire diameter. The Phase I processing will provide guidance for scale-up work in Phase II. Commercial Applications and other Benefits as described by the awardee: The improved cost-performance for this novel Nb3Sn conductor should have an immediate benefit for high field magnet applications. The successful demonstration of a prototype fusion machine based on an advanced cost effective Nb3Sn conductor would have enormous economic and social benefits. In addition, the technology could have application to NMR, which is on the verge of technological explosion with requirements in chemical research, biochemistry, pharmaceutical chemistry, polymer science, petroleum research, agricultural chemistry, and medicine.