Influence of local superconducting properties on pulsed field magnetization of YBCO bulk superconductor

Fujiyama, K.; Shiraishi, R.; Ohsaki, Hiroyuki

doi:10.1016/j.physc.2005.01.044

Cited by 17 publications

(6 citation statements)

References 6 publications

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“…Inhomogeneities occur during the growth process of c-axis seeded, single grain (RE)BCO bulk superconductors, resulting in the formation of growth section regions (GSRs) and growth sector boundaries (GSBs), as shown in figure 2, with a higher J c for the GSBs in comparison with the GSRs [98,[109][110][111]. These play a significant role in the magnetization of these materials, particularly for the PFM technique, where they can affect the magnitude and shape of the trapped field and the maximum temperature rise, and different results are observed in comparison to FC and ZFC, particularly for lower applied fields [104].…”

Section: Inhomogeneities In (Re)bco Bulk Superconductorsmentioning

confidence: 99%

Modelling of bulk superconductor magnetization

Ainslie

Fujishiro

2015

Supercond. Sci. Technol.

185

166

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This paper presents a topical review of the current state of the art in modelling the magnetization of bulk superconductors, including both (RE)BCO (where RE = rare earth or Y) and MgB 2 materials. Such modelling is a powerful tool to understand the physical mechanisms of their magnetization, to assist in interpretation of experimental results, and to predict the performance of practical bulk superconductor-based devices, which is particularly important as many superconducting applications head towards the commercialisation stage of their development in the coming years. In addition to the analytical and numerical techniques currently used by researchers for modelling such materials, the commonly used practical techniques to magnetize bulk superconductors are summarised with a particular focus on pulsed field magnetization (PFM), which is promising as a compact, mobile and relatively inexpensive magnetizing technique. A number of numerical models developed to analyse the issues related to PFM and optimise the technique are described in detail, including understanding the dynamics of the magnetic flux penetration and the influence of material inhomogeneities, thermal properties, pulse duration, magnitude and shape, and the shape of the magnetization coil(s). The effect of externally applied magnetic fields in different configurations on the attenuation of the trapped field is also discussed. A number of novel and hybrid bulk superconductor structures are described, including improved thermal conductivity structures and ferromagnet-superconductor structures, which have been designed to overcome some of the issues related to bulk superconductors and their magnetization and enhance the intrinsic properties of bulk superconductors acting as trapped field magnets (TFMs). Finally, the use of hollow bulk cylinders/tubes for shielding is analysed.

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Section: Inhomogeneities In (Re)bco Bulk Superconductorsmentioning

confidence: 99%

Modelling of bulk superconductor magnetization

Ainslie

Fujishiro

2015

Supercond. Sci. Technol.

185

166

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“…Inhomogeneities occur during the growth process of c-axis seeded, single-grain (RE)BCO bulk superconductors, resulting in the formation of GSBs and GSRs described above and shown in figure 1, with a higher critical current density for the GSBs in comparison with the GSRs [26][27][28][29]. Here the trapped field distribution and maximum temperature rise for an applied pulsed magnetic field is compared for a completely homogeneous bulk superconducting sample with an ab-plane J c of 1 × 10 8 A m −2 and an inhomogeneous sample with the same average J c , but with J c varying as a cosine function in the ab-plane [20], as shown in figure 11.…”

Section: Modelling Inhomogeneous Behaviourmentioning

confidence: 99%

Modelling and comparison of trapped fields in (RE)BCO bulk superconductors for activation using pulsed field magnetization

Ainslie

Fujishiro

Ujiie

et al. 2014

Supercond. Sci. Technol.

125

143

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The ability to generate a permanent, stable magnetic field unsupported by an electromotive force is fundamental to a variety of engineering applications. Bulk high temperature superconducting (HTS) materials can trap magnetic fields of magnitude over ten times higher than the maximum field produced by conventional magnets, which is limited practically to rather less than 2 T. In this paper, two large c-axis oriented, single-grain YBCO and GdBCO bulk superconductors are magnetised by the pulsed field magnetisation (PFM) technique at temperatures of 40 and 65 K and the characteristics of the resulting trapped field profile are investigated with a view of magnetising such samples as trapped field magnets (TFMs) in-situ inside a trapped flux-type superconducting electric machine. A comparison is made between the temperatures at which the pulsed magnetic field is applied and the results have strong implications for the optimum operating temperature for TFMs in trapped fluxtype superconducting electric machines. The effects of inhomogeneities, which occur during the growth process of single-grain bulk superconductors, on the trapped field and maximum temperature rise in the sample are modelled numerically using a 3D finite-element model based on the H-formulation and implemented in Comsol Multiphysics 4.3a. The results agree qualitatively with the observed experimental results, in that inhomogeneities act to distort the trapped field profile and reduce the magnitude of the trapped field due to localised heating within the sample and preferential movement and pinning of flux lines around the growth section regions (GSRs) and growth sector boundaries (GSBs), respectively. The modelling framework will allow further investigation of various inhomogeneities that arise during the processing of (RE)BCO bulk superconductors, including inhomogeneous J c distributions and the presence of current-limiting grain boundaries and cracks, and it can be used to assist optimisation of processing and PFM techniques for practical bulk superconductor applications.

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“…When the top handle rotates, the vessel moves up and down. Details of the experimental procedure is described in our former study [9], [10].…”

Section: A Basic Modelmentioning

confidence: 99%

Improvement of Magnetic Levitation Properties on Levitation System Using GdBCO Bulk Superconductors

Takao

Tanoue

Kameyama

et al. 2012

IEEE Trans. Appl. Supercond.

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We have developed a magnetic levitation system using a magnetic shielding effect of high temperature superconducting bulks. We have already succeeded to demonstrate principle of the levitation. In the paper, we tried to increase the levitation force. Firstly, when a ferromagnetic plate was put underside of a permanent magnet, the levitation force increased. And when the underside ferromagnetic plate was protruded from the magnet, the levitation force effectively increased furthermore. Lastly, the levitation force exceeded vehicle weight and the stable levitation became possible.

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Influence of local superconducting properties on pulsed field magnetization of YBCO bulk superconductor

Cited by 17 publications

References 6 publications

Modelling of bulk superconductor magnetization

Modelling of bulk superconductor magnetization

Modelling and comparison of trapped fields in (RE)BCO bulk superconductors for activation using pulsed field magnetization

Improvement of Magnetic Levitation Properties on Levitation System Using GdBCO Bulk Superconductors

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