Pulsed Field Magnetization of Bridge-Seeded, Bulk YBCO using Solenoid and Split Coils

The multi-seeding process has the potential to enlarge the sample size of (RE)BCO (where RE = rare earth or Y) single-grain, bulk superconductors with improved fabrication speed, and in previous studies on multi-seeding, a significant improvement was made in the alignment of the seeds in such samples using a novel bridge-seeding technique. In this paper, we report the experimental measurements of the pulsed field magnetization (PFM) of a 0°-0° bridge-seeded Y-Ba-Cu-O (YBCO) sample. The PFM is carried out using a solenoid coil, as well as a split coil arrangement with an iron yoke, at temperature of 65, 40 and 20 K, and the resultant trapped fields and magnetic flux dynamics for these two PFM techniques are compared. It is shown that such bridge-seeded bulk YBCO can be fabricated that performs as a bulk magnet with trapped fields comparable to or better than standard, single-seeded high-$J_\text{c}$ samples, with the potential of enlarging the sample size. Furthermore, the split coil arrangement with an iron yoke is useful to enhance the trapped field and has a positive effect on the maximum temperature rise in the sample, which increases at lower temperatures and seriously impacts the achievable trapped field from PFM.The work of M. D. Ainslie was supported in part by the Royal Academy of Engineering Research Fellowship and in part by the Royal Society International Exchanges Scheme under Grant IE131084. The work of H. Fujishiro was supported in part by the Open Partnership Joint Projects of the Japan Society for the Promotion of Science (JSPS) Bilateral Joint Research Projects, and in part by the JSPS KAKENHI under Grants 23560002 and 15K04646