A "permanent" high-temperature superconducting magnet operated in thermal communication with a mass of solid nitrogen

Benjamin J. Haid, Haigun Lee, Yukikazu Iwasa, Sang Soo Oh, Young Kil Kwon, Kang Sik Ryu

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


A new design for a portable "permanent" superconducting magnet system is explored. The design involves a persistent-mode high-temperature superconducting (HTS) magnet that is cooled by a solid heat capacitor. The system is an alternative to permanent low-temperature superconducting (LTS) magnet systems where the magnet is cooled by a bath of liquid helium. An apparatus was constructed to demonstrate stable operation of a permanent magnet wound with Bi2223/Ag conductor while in thermal communication with a mass of solid nitrogen. The apparatus includes a room-temperature bore and can function while it stands alone, detached from its cooling source, power supply, and vacuum pump. The magnet is operated in the 20-40 K temperature range. This apparatus is the first to demonstrate the operation of a superconducting magnet with a permissible temperature variation exceeding a few degrees kelvin. Models are developed to predict the experimental system's warming trend and magnetic field decay. The models are validated with a good agreement between simulations based on these models and experimental results. The results indicate that present HTS conductor critical current and index are not yet sufficient to provide field strengths and field decay time constants that are required for typical persistent-mode applications.

Original languageEnglish
Pages (from-to)229-244
Number of pages16
Issue number3-4
Publication statusPublished - 2002 Mar
Externally publishedYes

Bibliographical note

Funding Information:
Work supported in part by the Korea Electrotechnology Research Institute and Daesung Cable Co., Korea.


  • HTS magnet
  • Persistent-mode
  • Solid nitrogen

ASJC Scopus subject areas

  • General Materials Science
  • General Physics and Astronomy


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