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Pulsed field magnetization of 0°-0° and 45°-45° bridge-seeded Y-Ba-Cu-O bulk superconductors


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Authors

Ainslie, MD 
Zou, J 
Mochizuki, H 
Fujishiro, H 
Shi, YH 

Abstract

Large, single-grain (RE)BCO (where RE = rare earth or Y) bulk superconductors with complicated geometries are required for a variety of potential applications, such as rotating machines, magnetic bearings and magnetic separation. As a consequence, the top multi-seeded melt growth process has been studied over many years in an attempt to deliver large, single grains for practical applications. Among these techniques, the so-called bridge-seeding produces the best alignment of two seeds during melt processing of multi-seed samples. In this paper, the trapped field performance and magnetic flux dynamics of two bridge-seeded, multi-seed samples magnetized by pulsed field magnetization (PFM) are analysed: one with a 45⁰-45⁰ and another with a 0⁰-0⁰ bridge seed. Based on an analysis of the flux penetration across the seeds and in-between the seeds of the 45⁰-45⁰ multi-seed sample, an estimated Jc distribution over the ab-plane was determined, which provides the basis for further analysis via numerical simulation. A 3D finite-element model, developed to qualitatively reproduce and interpret the experimental results, was employed to investigate the influence of the length of the bridge seed for such multi-seed samples. The simulation results agree well with the observed experimental results, in that the multi-seed sample’s particular inhomogeneous Jc distribution acts to distort the trapped field profile from a traditional conical Bean’s profile, which is determined by the length and direction of the bridge seed on the bulk surface.

Description

Keywords

bulk superconductors, multi-seeding, bridge-shaped seeds, trapped field magnets, pulsed field magnetization, numerical modelling, finite element method (FEM) modelling

Journal Title

Superconductor Science and Technology

Conference Name

Journal ISSN

0953-2048
1361-6668

Volume Title

28

Publisher

IOP Publishing
Sponsorship
Royal Academy of Engineering (RAEng) (10216/113)
Royal Society (IE131084)
Engineering and Physical Sciences Research Council (EP/P00962X/1)
Engineering and Physical Sciences Research Council (EP/K02910X/1)
Japan Society for the Promotion of Science (15K04646)
Mark Ainslie would like to acknowledge the support of a Royal Academy of Engineering Research Fellowship. Jin Zou would like to acknowledge the support of Churchill College, Cambridge, the China Scholarship Council and the Cambridge Commonwealth, European and International Trust. Hiroyuki Fujishiro would like to acknowledge support in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan. This research was also supported in part by a Royal Society International Exchanges Scheme grant, IE131084.