Large Vessels of Bi Oxide Superconductor for Magnetic Shield

Koike, Atsushi; Hoshino, Kazutomo; Kotaka, H.; Sudoh, E.; Katoh, Kazuhiko; Ohta, Hiroshi

doi:10.1007/978-4-431-68195-3_232

Cited by 2 publications

(1 citation statement)

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“…The configuration where the tube wall and the cap are grown in the same process clearly exhibits the best shielding properties in transverse field. This underlines the importance of using vesselshaped shields [34,41] and, more generally, of achieving superconducting joints between the superconducting components. In addition to the Buffer-Aided Top Seeded Melt Growth presented in this paper, multi-seeding [24] and the creation of artificially engineered boundaries [42][43][44][45] allowing high currents through melt-textured monoliths are also very promising approaches.…”

Section: Discussionmentioning

confidence: 90%

Magnetic Shielding of Open and Semi-closed Bulk Superconductor Tubes: The Role of a Cap

Wera

Fagnard

Hogan

et al. 2019

IEEE Trans. Appl. Supercond.

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In this paper we investigate the magnetic shielding of hollow and semi-closed bulk superconducting tubes at 77 K. We first consider the properties of a commercial Bi-2223 tube closed by a disk-shaped cap placed against its extremity. The results are compared to those obtained on a bulk large grain Y-Ba-Cu-O (YBCO) tube produced by buffer-aided top seeded melt growth. In this process, the disk-shaped pellet and the tubular sample are grown together, resulting in a tube naturally closed at one extremity. The field to be shielded is either parallel or perpendicular to the main axis of the tube. The experimental results are compared with the results of finite element numerical modelling carried out either in 2D (for the axial configuration) or 3D (for the transverse configuration). In the axial configuration, the results show that the shielded volume can be enhanced easily by increasing the thickness of the cap. In the transverse configuration, the results show the critical role played by the superconducting current loops flowing between the tube and the cap for magnetic shielding. If the tube and the cap are separated by a non-superconducting joint or air gap, the presence of a cap leads to only a small improvement of the transverse shielding factor, even for a configuration where the gap between the cap and the tube contains a 90° bend. The cap leads to a significant increase in the transverse shielding when the cap and the tube are naturally grown in the same process, i.e. made of a continuous superconducting material. The experimental results can be reproduced qualitatively by 3D numerical modelling.

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