A Novel Way to Dope Ti in Nb3Sn Conductor to Reduce A15 Grain Size and non- Cu Critical Current at High Fields Topic 26A

This proposal is submitted in response to the SBIR/STTR High Energy Physics Topic 26(a), “Superconductor Technologies for Particle Accelerators, (a) High-Field Superconducting Wire Technologies for Magnets”. Grant applications are sought to develop new or improved superconducting wire for high field magnets that operate at 16 Tesla (T) field and higher. The need is for strands that operate at 15 to 25 T. Hyper Tech has fabricated Nb3Sn strands with our tube approach strand with 217 filaments at 0.7 mm OD in kilometers lengths and the deff sizes of 35 micros and conductor performance of 2500 A/mm2 at 12 T; Hyper Tech has also fabricated Nb3Sn strand with over 3000 A/mm2 at 12 T using the internal-Sn distributed barrier method; Currently Hyper Tech is working on creating artificial pinning centers for our tube type Nb3Sn strands which has successfully doubled the layer Jcs for binary Nb3Sn and we have made a 61 restack of the tube type subelement with artificial pinning centers which was drawn down to 0.31 mm with 34 m subelements. In this Phase I, we will develop a novel way to dope Ti in the structure to further refining the grain size in A15 area compared to the APC binary approach resulting in higher Bc2 and higher non-Cu Jc at higher fields. In particular, we will focus on approaches which not only demonstrate that artificial pins can be generated in the Nb3Sn Ti doped strands, but that they can be generated with an approach that can be scaled to high current density (Je) , and long length production (a scalable approach). This approach will demonstrate separation of the oxygen and Ti diffusion paths resulting in enhanced reaction control. We will demonstrate this method could be used in doped Nb3Sn strands and demonstrate its substantial billet lengths of over 3 kilometers at 1.0 mm diameters with subelements of 50 m or less in a proposed follow-on Phase II. The other commercial applications of this advanced Nb3Sn strands are high field 7-11T MRI, NMR systems, superconducting accelerators - protron radiation for cancer treatment, SMES, and high field magnetic separation. According to a U.S. EPA article, more than 97% of the 15,000 accelerators in use around the world have commercial applications, e.g. in the diagnosis and treatment of cancer, the locating of oil and minerals in the earth, the processing of semiconductor chips for computers, the determination of the age of materials through radiocarbon dating, the sterilizing of medical equipment and food products.