Growth of YBCO single domains through an array of holes for FCL c-axis superconducting elements

184

166

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.

Section: Improved Thermal Conductivity Composite Structuresmentioning

confidence: 99%

Modelling of bulk superconductor magnetization

Ainslie

Fujishiro

2015

184

166

“…The sample was produced at CRISMAT (Caen, France) by the top-seeded melt-textured growth process from a Measurement of the magnetic field inside the holes of a drilled bulk HTS 6 drilled preform [32]. The details of the sample preparation can be found in Ref.…”

Section: Ybco Drilled Samplementioning

confidence: 99%

“…Measurements of the magnetic flux were carried out inside the holes of a YBCO drilled cylinder containing 68 artificially patterned holes. The sample was produced at CRISMAT (Caen, France) by the top-seeded melt-textured growth process from a Measurement of the magnetic field inside the holes of a drilled bulk HTS 6 drilled preform [32]. The details of the sample preparation can be found in Ref.…”

Section: Ybco Drilled Samplementioning

confidence: 99%

Measurement of the magnetic field inside the holes of a drilled bulk high-T_csuperconductor

Lousberg

Fagnard

Noudem

et al. 2009

Abstract.We use macroscopic holes drilled in a bulk YBCO superconductor to probe its magnetic properties in the volume of the sample. The sample is subjected to an AC magnetic flux with a density ranging from 30 mT to 130 mT and the flux in the superconductor is probed by miniature coils inserted in the holes. In a given hole, three different penetration regimes can be observed: (i) the shielded regime, where no magnetic flux threads the hole; (ii) the gradual penetration regime, where the waveform of the magnetic field has a clipped sine shape whose fundamental component scales with the applied field; and (iii) the flux concentration regime, where the waveform of the magnetic field is nearly a sine wave, with an amplitude exceeding that of the applied field by up to a factor of two. The distribution of the penetration regimes in the holes is compared with that of the magnetic flux density at the top and bottom surfaces of the sample, and is interpreted with the help of optical polarized light micrographs of these surfaces. We show that the measurement of the magnetic field inside the holes Measurement of the magnetic field inside the holes of a drilled bulk HTS 2 can be used as a local characterization of the bulk magnetic properties of the sample.

“…Sample E does not contain holes and is used as a reference sample, processed under the same conditions. A detailed description of the melt processing can be found in [13][14][15] for 288 h. Optical inspection of the samples leads to the assumption that sample E is not fully oxygenated, especially because it shows a large bright area depleted of twins on its polished top surface, exactly where subsequent investigations revealed very poor superconducting properties. For sample D bright areas could not be found.…”

Section: Sample Preparationmentioning

confidence: 99%

Hall probe mapping of melt processed superconductors with artificial holes

Haindl

Hengstberger

Weber

et al. 2005

Melt processed superconductors containing mechanically drilled holes parallel to the c-axis were investigated by means of Hall scans of the trapped field distribution and the magnetoscan technique. We show that the remnant flux profiles are affected by the perforation in different ways. The location of the holes can be resolved by field mapping at activation fields below that for complete penetration of the bulk. The magnetoscan technique allows one to spatially localize the array of holes.