The High Field Laboratory for Superconducting Materials (HFLSM), Institute for Materials Research, Tohoku University has demonstrated the first practical cryocooled superconducting magnets using a GM-cryocooler and high temperature superconducting current leads. For high magnetic field research, various kinds of easy-to-operate cryocooled superconducting magnets such as wide bore, high field, and new functional magnets have been constructed. Recently, the HFLSM succeeded in developing a cryocooled 18.1 T high temperature superconducting magnet and a cryocooled 27.5 T hybrid magnet. This paper reviews cryocooled superconducting magnet technology and relevant new research areas.
A cryocooled superconducting magnet with a 360-mm room-temperature bore has been developed for hybrid magnets. Magnetic fields of 9.5 T in individual mode operation and 27.5 T in hybrid mode operation were successfully achieved when used in combination with a high-power water-cooled resistive magnet, although quenching occurred at 8.6 T during the first operation due to an unexpected rise in temperature. We discuss the thermal behavior of the innermost coil, where quenching was generated, through the analysis of temperature distribution measurement and two-dimensional thermal conductivity.