How to overcome the demagnetization of superconducting Halbach arrays?

Houbart, M., Fagnard, J.-F., Dular, J., Dennis, A.R., Namburi, D.K., Durrell, J. H., Geuzaine, C., Vanderheyden, B. and Vanderbemden, P. (2023) How to overcome the demagnetization of superconducting Halbach arrays? Superconductor Science and Technology, 36(11), 115012. (doi: 10.1088/1361-6668/acf904)

Abstract

Assembling trapped-field superconducting magnets with mutually orthogonal magnetizations directions in a Halbach array configuration offers the prospect of generating both high fields and large field gradients. A major issue when assembling bulk superconductors in a Halbach array, however, consists in the alteration of the initial current density distribution during the assembly process. This reorganization of supercurrent loops limits the field generated by the system. We investigate two methods for reducing this demagnetization effect. The first method consists of using stacked tapes instead of bulk superconductors. For the second method, we propose a procedure leading to a re-magnetizing the superconductors of the array after the assembly. The procedure consists in putting two superconductors on top of one another, magnetizing them along the vertical direction, and then keeping the pair in place while two other superconductors, magnetized in an horizontal direction, are approached from left and right. The top central sample is then removed from the array, thereby providing the desired re-magnetization of the bottom one. The benefits of this procedure was investigated by finite element modelling and experiments carried out at 77 K both with bulk YBa2Cu3O7−x superconductors (∼14×14×14 mm3) and with stacks of second generation YBa2Cu3O7−x tapes from Superpower (∼12×12×12 mm3). The flux density measured above the array is compared to analytical results and finite element simulations. The results show that a re-magnetization of the central sample occurs, which allows the maximum field generated with Halbach arrays made of three bulk superconductors or three stacked tapes to be increased by 5% and 11% respectively. Numerical modelling shows that using a taller top sample with this method allows to recover almost the full potential of the array.

• Item Type: Articles
• Additional Information: This work was supported by the Fonds de la Recherche Scientifique—FNRS under Grant CDR No. J.0218.20 (35325237). Michel Houbart is recipient of an FRS-FNRS Research Fellow grant.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Namburi, Dr Devendra Kumar
• Authors: Houbart, M., Fagnard, J.-F., Dular, J., Dennis, A.R., Namburi, D.K., Durrell, J. H., Geuzaine, C., Vanderheyden, B., and Vanderbemden, P.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Superconductor Science and Technology
• Publisher: IOP Publishing
• ISSN: 0953-2048
• ISSN (Online): 1361-6668
• Published Online: 06 October 2023
• Copyright Holders: Copyright © 2023 IOP Publishing Ltd
• First Published: First published in Superconductor Science and Technology 36(11): 115012
• Publisher Policy: Reproduced in accordance with the publisher copyright policy