SBIR-STTR Award

In the near future, there will be an urgent need for large quantities of Nb3Sn superconductor for the International Thermonuclear Experimental Reactor (ITER), an experimental fusion device, and the DOE has only a few domestically located companies that are capable of supplying this need. Two of these are subsidiaries of European companies that already have orders and commitments to the EU fusion program. There is a serious need for a U.S. company that is interested in, and capable of, helping to supply some of the requirements. In this project, small quantities of material meeting the U.S. specifications will be made in Phase and scaled-up in Phase II to full production-size billets. The ultimate goal is to demonstrate that a U.S. company can satisfy the DOE requirements for this superconductor material. In Phase I, two 88.9 mm (3.5") Ø billets, both of a four-row drilled design, one with Nb filaments and the other with Nb7.5wt.%Ta filaments, will be made into two groups of 19 and 37-subelement restacks. Half will have tin cores and the other half Sn2wt.%Ti cores. These will be tested for current carrying capability and losses and the most economical, i.e., the one that meets the specifications with the largest margin, will be selected for scale-up in Phase II.

Commercial Applications and Other Benefits as described by the awardee:
In addition to being used in ITER and other fusion applications, the resultant material should have appliation to open area Magnetic Resonance Imaging (MRI) where the patient is more accessible to the surgeon. MRI is the largest commercial application of low temperature superconductors (LTS). Other applications include Nuclear Magnetic Resonance and High Energy Physics - for the latter, the materials could find use in high magnetic field magnets for accelerator applications

In the near future, there will be an urgent need for large quantities of Nb3Sn superconductor for the International Thermonuclear Experimental Reactor (ITER), an experimental fusion device. However, the DOE has only a few domestically-located companies that are capable of supplying this need, and two of these are subsidiaries of European companies that have orders and commitments to the EU fusion program. Thus, there is a serious need for a U.S. company that can supply some of this superconductor. This project will demonstrate that a United States company can supply superconductor strands that meet toroidal-field specifications from production-size billets. In Phase I, several lengths of strand were made from two small billets, without any fabrication problems. The aim was to meet the specification for the central solenoid conductor, which has lower electrical loss and slightly lower critical current density. The material produced had a lower critical current density than required, but the reasons for this result were identified and are not thought to be insurmountable. Phase II will focus on reducing the distortion of the filaments, enlarging the billets, controlling the spacing-to-diameter ratio of the superconductor rods, and improving the critical current density. First, small billets will be fabricated to enable the process to be refined and modified to meet the toroidal-field specification. Afterwards, large billets will be fabricated to demonstrate the viability of a domestic strand supplier.

Commercial Applications and Other Benefits as described by the awardee:
In addition to the fusion application, Nb3Sn superconductors should find use in open-area Magnetic Resonance Imaging (MRI), where the patient is more accessible to the surgeon. (MRI is the largest commercial application of low temperature superconductors.) There is also a need for this type of product in High Energy Physics research and in Nuclear Magnetic Resonance