Processing of bulk MgB2 superconductors for application in fault current limiters

Tatiana Prikhna, Vladimir Sokolovsky, Victor Meerovich, Michael Eisterer, Athanasios Mamalis, Artem Kozyrev, Wolfgang Gawalek, Viktor Moshchil, Vladimir Sverdun, Harald W. Weber, Valeriy Kovylaev, Wilfried Goldacker, Myroslav Karpets, Tatiana Basyuk, Minzhi Wu, Nina Sergienko

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Fault current limiters (FCL) require superconducting (SC) materials which can provide a definite rate of response to a fault event resulting in the SC – normal state reversible transition. The main characteristics determined the material suitability are the critical current density, jc, thermal conductivity and capacity which are strongly determined by manufacturing technology, in particular, of MgB2. In the paper we estimate the jc of bulk MgB2 samples by the vibrating magnetometer and inductive, contactless transformer, method using ring samples. The bulk MgB2 samples were produced under 30 MPa (hot pressing) and 2 GPa (quasihydrostatic pressing) at 800- 1050 ºC from different initial ingredients (Mg and B or MgB2 with and without additions). It is shown that the technology process and initial ingredients strongly influence the distribution of boron- and oxygen-enriched nanosized inhomogenities in MgB2 matrix, connectivity between SC grains, material porosity and, as result, the SC properties. The transformer method gives the jc in the range from 1.6·104 up to 6.3·104 A/cm2 at about 4 K while using magnetometer measurements the jc is estimated from 2.24·105 up to 5.1·105 A/cm2 at 10 K in self magnetic fields. The contradictions in the jc estimated by different methods can be explained by instability of the SC state of MgB2, caused by variation of the applied magnetic field. Using the transformer method AC losses per a cycle before quenching for the best materials were estimated around 0.75-1 J/cm3, while the power of losses was about 200 W. The FCL model with rings cut out from SC MgB2 materials prepared using various technologies demonstrated that MgB2 is a promising material for application in inductive FCLs.

Original languageEnglish
Title of host publicationApplied Electromagnetic Engineering for Advanced Materials from Macroto Nanoscale
EditorsA.G. Mamalis, Antonios G. Kladas, Masato Enokizono, Masato Enokizono, Vladimir Lazarov
PublisherTrans Tech Publications Ltd
Pages32-37
Number of pages6
ISBN (Print)9783035710267
DOIs
StatePublished - 1 Jan 2016
Event9th Japanese-Mediterranean Workshop on Applied Electromagnetic Engineering for Magnetic, Superconducting, Multifunctional and Nano Materials, 2015 - Sofia, Bulgaria
Duration: 5 Jul 20158 Jul 2015

Publication series

NameMaterials Science Forum
Volume856
ISSN (Print)0255-5476
ISSN (Electronic)1662-9752

Conference

Conference9th Japanese-Mediterranean Workshop on Applied Electromagnetic Engineering for Magnetic, Superconducting, Multifunctional and Nano Materials, 2015
Country/TerritoryBulgaria
CitySofia
Period5/07/158/07/15

Keywords

  • Bulk MgB
  • Critical current density
  • Fault current limiter
  • Nanostructure
  • Pressure

ASJC Scopus subject areas

  • Materials Science (all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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