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

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 are analyzed: one with a 45°–45° and another with a 0°–0° bridge seed. Based on an analysis of the flux penetration across the seeds and in-between the seeds of the 45°–45° multi-seed sample, an estimated J c distribution over the ab-plane is determined, which provides the basis for further analysis via numerical simulation. A three-dimensional 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.

[1]  T. Sung,et al.  Multiseeding with (100)/(100) grain junctions in top-seeded melt growth processed YBCO superconductors , 2000 .

[2]  T. A. Coombs,et al.  Comparison of first‐ and second‐order 2D finite element models for calculating AC loss in high temperature superconductor coated conductors , 2011 .

[3]  Wei Zhai,et al.  Numerical simulation and analysis of single grain YBCO processed from graded precursor powders , 2015 .

[4]  John R. Hull,et al.  TOPICAL REVIEW: Superconducting bearings , 2000 .

[5]  Weijia Yuan,et al.  Numerical Analysis of AC Loss Reduction in HTS Superconducting Coils Using Magnetic Materials to Divert Flux , 2013, IEEE Transactions on Applied Superconductivity.

[6]  T. Sung,et al.  Effects of the seed distance on the characteristics of the (100)/(100) junctions of top-seeded melt growth processed YBCO superconductors using two seeds , 2000 .

[7]  S. Nariki,et al.  Melt-processed Gd–Ba–Cu–O superconductor with trapped field of 3 T at 77 K , 2005 .

[8]  S. Haindl,et al.  Grain boundaries in multi-seeded melt-grown superconductors , 2005, IEEE Transactions on Applied Superconductivity.

[9]  Francesco Grilli,et al.  A full 3D time-dependent electromagnetic model for Roebel cables , 2013 .

[10]  C. P. Bean.  Magnetization of hard superconductors , 1962 .

[11]  D. Cardwell,et al.  Properties of grain boundaries in bulk, melt processed Y–Ba–Cu–O fabricated using bridge-shaped seeds , 2012 .

[12]  Mark D. Ainslie,et al.  A trapped field of 17.6 T in melt-processed, bulk Gd-Ba-Cu-O reinforced with shrink-fit steel , 2014, 1406.0686.

[13]  M. Ainslie,et al.  Modelling of bulk superconductor magnetization , 2015 .

[14]  Wei Zhai,et al.  A Comparison of 0°–0° and 45°–45° bridge‐Seeded, YBCO single grains , 2013 .

[15]  Masato Murakami,et al.  High-temperature superconductor bulk magnets that can trap magnetic fields of over 17 tesla at 29 K , 2003, Nature.

[16]  P. Vanderbemden,et al.  Numerical modelling and comparison of MgB2 bulks fabricated by HIP and infiltration growth , 2015 .

[17]  D. Cardwell,et al.  Bulk YBCO seeded with 45°–45° bridge-seeds of different lengths , 2012 .

[18]  Mitsuru Izumi,et al.  An overview of rotating machine systems with high-temperature bulk superconductors , 2012 .

[19]  C. Plummer,et al.  Dependence of the shape of the resistive transition on composite inhomogeneity in multifilamentary wires , 1987 .

[20]  Dean J. Miller,et al.  Controlled growth of bulk bicrystals and the investigation of microstructure‐property relations of YBa2Cu3Ox grain boundaries , 1996 .

[21]  C. P. Bean,et al.  Magnetization of High-Field Superconductors , 1964 .

[22]  Jakob Rhyner,et al.  Magnetic properties and AC-losses of superconductors with power law current-voltage characteristics , 1993 .

[23]  Min Zhang,et al.  3D modeling of high-Tc superconductors by finite element software , 2011 .

[24]  G. Hong,et al.  Multi-seeded melt growth processed YBCO superconductors , 2001 .

[25]  T. A. Coombs,et al.  Numerical solution of critical state in superconductivity by finite element software , 2006 .

[26]  K. Iida,et al.  A practical route for the fabrication of large single-crystal (RE)–Ba–Cu–O superconductors , 2005, Nature Materials.

[27]  D. Cardwell,et al.  Development of a generic seed crystal for the fabrication of large grain (RE)–Ba–Cu–O bulk superconductors , 2005 .

[28]  Jin Zou,et al.  Modelling and comparison of trapped fields in (RE)BCO bulk superconductors for activation using pulsed field magnetization , 2014 .

[29]  T. Oka.  Processing and applications of bulk HTSC , 2007 .

[30]  Mark D. Ainslie,et al.  Calculating transport AC losses in stacks of high temperature superconductor coated conductors with magnetic substrates using FEM , 2012 .

[31]  Mark D. Ainslie,et al.  An improved FEM model for computing transport AC loss in coils made of RABiTS YBCO coated conductors for electric machines , 2011 .