Thermal analysis of the cryocooled superconducting magnet for the liquid helium-free hybrid magnet

Masayuki Ishizuka, Takataro Hamajima, Tomoyuki Itou, Junji Sakuraba, Gen Nishijima, Satoshi Awaji, Kazuo Watanabe

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


The liquid helium-free hybrid magnet, which consists of an outer large bore cryocooled superconducting magnet and an inner water-cooled resistive magnet, was developed for magneto-science in high fields. The characteristic features of the cryogen-free outsert superconducting magnet are described in detail in this paper. The superconducting magnet cooled by Gifford-McMahon cryocoolers, which has a 360 mm room temperature bore in diameter, was designed to generate high magnetic fields up to 10 T. The hybrid magnet has generated the magnetic field of 27.5 T by combining 8.5 T generation of the cryogen-free superconducting magnet with 19 T generation of the water-cooled resistive magnet. The superconducting magnet was composed of inner Nb3Sn coils and outer NbTi coils. In particular, inner Nb3Sn coils were wound using high-strength CuNi-NbTi/Nb3Sn wires in consideration of large hoop stress. Although the cryocooled outsert superconducting magnet achieved 9.5 T, we found that the outsert magnet has a thermal problem to generate the designed maximum field of 10 T in the hybrid magnet operation. This problem is associated with unexpected AC losses in Nb3Sn wires.

Original languageEnglish
Pages (from-to)S1027-S1029
JournalPhysica C: Superconductivity and its Applications
Issue numberSUPPL.1
Publication statusPublished - 2010 Dec


  • Cryocooled superconducting magnet
  • High magnetic field
  • High-strength NbSn wire
  • Hybrid magnet
  • Magneto-science


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