Improvement of a Large Bore Cryogen-Free Superconducting Magnet for a Hybrid Magnet

T. Tsurudome, Y. Mikami, A. Hashimoto, H. Mitsubori, H. Ookubo, J. Sakuraba, T. Kato, K. Watazawa, K. Watanabe, S. Awaji, H. Oguro, S. Hanai, S. Ioka

Research output: Contribution to journalArticlepeer-review


A 360-mm room-temperature bore cryogen-free superconducting magnet (CSM), consisting of Nb 3Sn coils and NbTi coils, for a hybrid magnet (HM) has generated the maximum magnetic field of 9.5 T. However, the magnetic field of the CSM has been limited to 8.5 T in the hybrid magnet mode because of a cooling problem. As a result, the hybrid magnet composed of a 19-T water-cooled resistive magnet (WM) had the utmost field generation of 27.5 T. Therefore, we improved the CSM to generate higher magnetic fields. For the improvement of the cooling problem, Nb 3Sn coils were replaced, and thermal conduction was improved between coils and a 4K-GM cryocooler. Furthermore, support structures with a tensile strength over 80 kN and a spring support were adopted against the magnetic force to support the self-weight of coils and to absorb stress caused by thermal contraction difference between each coil. After the improvement, the CSM generated 9.5 T within 1 h and the maximum magnetic field of 9.7 T in a 360-mm room-temperature bore. The HM succeeded in generating 28 T in a 32-mm room-temperature bore with the CSM operated at 9.0 T.

Original languageEnglish
Article number7397976
JournalIEEE Transactions on Applied Superconductivity
Issue number3
Publication statusPublished - 2016 Apr


  • Cryogen-free superconducting magnet
  • Nb3Sn wire
  • high magnetic field
  • hybrid magnet
  • thermal properties

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


Dive into the research topics of 'Improvement of a Large Bore Cryogen-Free Superconducting Magnet for a Hybrid Magnet'. Together they form a unique fingerprint.

Cite this