'Electromaglev' - Magnetic levitation of a superconducting disc with a DC field generated by electromagnets: Part 1. Theoretical and experimental results on operating modes, lift-to-weight ratio, and suspension stiffness

Yukikazu Iwasa, Haigun Lee

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

We present results of a comprehensive study, both theoretical and experimental, of an 'electromaglev' system, in which a high-temperature superconducting bulk sample, e.g. YBa2Cu3O7-δ (YBCO), is levitated stably in a DC magnetic field generated by electromagnets placed underneath the floating object. Results of the zeroth-order theory agree quite well with experimental results on lift-to-weight ratio and suspension stiffness for three bulk samples: (1) a solid YBCO disc; (2) a YBCO annulus; and (3) a YBCO annulus with a neodymium-iron-boron (Nd-Fe-B) permanent magnet disc (PMD) filling the centre. The experiment has also verified the need to satisfy two requirements to achieve stable levitation with a DC magnetic field only: (1) the spatial flow of the supercurrent in the sample must have at least two degrees of freedom; and (2) the electromagnets must generate a magnetic field profile that satisfies spatial requirements for lateral arid pitch stability. A permanent magnet disc has only one degree of freedom for its Amperian current, thus it cannot be levitated stably in this system; the experiment has also demonstrated that an HTS solenoid (wound with silver-sheathed BSCCO-2223 tape) cannot be levitated stably, because the solenoid supercurrent flow is also restricted to the azimuthal direction only. The zeroth-order theory together with the Bean model shows that the supercurrent induced in a YBCO sample is independent of the critical current density, Jc, of the material but is directly proportional to the axial component of the field and that the lift of the sample is directly proportional to the product of the axial and radial components of the magnetic field generated by the electromagnets.

Original languageEnglish
Pages (from-to)807-816
Number of pages10
JournalCryogenics
Volume37
Issue number12
DOIs
Publication statusPublished - 1997
Externally publishedYes

Keywords

  • Active maglev
  • Magnetic levitation
  • YBCO disk

ASJC Scopus subject areas

  • Materials Science(all)
  • Physics and Astronomy(all)

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