Speaker
Description
Bi-2212 round wire is currently being developed for high-field magnet applications. The large critical current densities of present state-of-the-art Bi-2212 strands, coupled with their relatively ductile Ag/Ag alloy matrix, leads to stress-limited performance in many high field solenoids. The critical current degrades as a function of stress due to the onset of progressive fracture of the Bi-2212 filaments. For this reason, strand reinforcement is highly desirable to increase the stress limits at higher fields. Reinforcement can be achieved in a variety of ways, however, the application of a high-strength metallic alloy bonded to the long flat faces of rectangular strands of Bi-2212 (produced by Solid Material Solutions) show promising preliminary results in doubling the stress limits of 2212 strands (from 150 MPa to 300 MPa). Research in the application of these techniques to produce a strengthened HTS strand and their characterization for high field coil technologies is ongoing. Here we report on the challenges and results when reinforcing Bi-2212 for high field applications.
Key words: Bi-2212, high field magnet, conductor development, stress, strain, coil technology
Acknowledgement: This work was performed at the National High Magnetic Field Laboratory, supported by National Science Foundation Cooperative Agreement No. DMR-1157490 and the State of Florida and also supported by the US Department of Energy Office of High Energy Physics under grant 227011-520-032288 and the National Institute of Health under grant R21GM111302.
