Characteristics of New Nb3Sn Strand Developed in Korea for High Field Applications

The continuing trend in magnet technology is toward higher field, and for large scale magnetic coils low temperature superconductors still dominate with Nb3Sn being the material of choice. Kiswire Advanced Technology Co. Ltd. (KAT) based in Daejeon, Korea has recently developed Nb3Sn strand with critical current densities of the non-Cu area in excess of 2000 A/mm ² at 4.2 K and 12 T background field. At 16 T, these strands are able to carry around 200 A under thermal strain, and critical current measurements under axial strain have shown peak critical currents above 300 A. The designs of the new Nb3Sn strands by KAT are presented as well as the technique and issues involved in the measurements of their critical currents under axial strain. These strands approach the technical requirements set for next generation superconducting facilities to be constructed in Korea which include a high magnetic field conductor test facility and the K-DEMO tokamak.