Design and Test Results of a Cryogenic Cooling System for a 25-T Cryogen-Free Superconducting Magnet

Masahiko Takahashi, Sadanori Iwai, Hiroshi Miyazaki, Taizo Tosaka, Kenji Tasaki, Satoshi Hanai, Shigeru Ioka, Hiroyuki Takigami, Kazuo Watanabe, Satoshi Awaji, Hidetoshi Oguro, Yuji Tsuchiya

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


A cryogenic cooling system for a 25-T cryogen-free superconducting magnet (25T-CSM) was developed. The 25T-CSM consisted of 11-T high-Tc superconducting (HTS) coils and 14 T low-Tc superconducting (LTS) coils. The HTS coils, which had about 10-W AC-loss, were cooled to about 10 K by two GM cryocoolers and a helium gas circulation unit. In this system, the gas flow rate had an optimized value and was controlled by a mass flow controller. The LTS coils were cooled to about 4 K by two GM/JT cryocoolers. Each GM/JT cryocooler had two sets of precooling gas lines. These pre-cooling lines were cooled by two single-stage GM cryocoolers and the HTS coil cooling system via a heat exchanger, between the HTS gas circulation line and the LTS cool-down line. As a result of cooling test of the 25T-CSM, the LTS coils and HTS coils were cooled from room temperature to 4.3 K and 4.6 K within 164 h (about seven days), respectively. During the excitation test of the HTS coils, their maximum temperature increased to 7.6 K, which was still sufficiently low.

Original languageEnglish
Article number7862758
JournalIEEE Transactions on Applied Superconductivity
Issue number4
Publication statusPublished - 2017 Jun


  • Cooling system
  • REBCO coil
  • high-field magnet
  • superconducting magnet


Dive into the research topics of 'Design and Test Results of a Cryogenic Cooling System for a 25-T Cryogen-Free Superconducting Magnet'. Together they form a unique fingerprint.

Cite this