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

M D Ainslie, J Zou, H Mochizuki, H Fujishiro, Y-H Shi, A R Dennis, D A Cardwell
2015 Superconductors Science and Technology  
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 multiseeded 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 bridgeseeding produces the best alignment of two seeds during melt
more » ... 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 J c 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 J c 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. Keywords: bulk superconductors, multi-seeding, bridge-shaped seeds, trapped field magnets, pulsed field magnetization, numerical modelling, finite element method (FEM) modelling c c c J J J J J J J    .
doi:10.1088/0953-2048/28/12/125002 fatcat:wn3rl5nxvvc35jxgqwbfqmhinq