In order to realize a hybrid magnet with no need of liquid helium for operation, we have designed a 28 T cryogen-free hybrid magnet with a 32 mm room temperature experimental bore, and actually tested to generate the peak field of 27.5 T. An easy-to-operate cryogen-free hybrid magnet is now operating for basic research in high fields up to 27 T at low temperatures down to 40 mK, using a dilution refrigerator. In addition, we are intending to develop a 100 mm wide bore water-cooled resistive insert magnet combined with a cryogen-free superconducting outsert magnet for X-ray diffraction measurements in steady magnetic fields up to 20 T.
It found that YBa2Cu3O7 (Y123) coated conductor tape with Hastelloy substrate has the excellent mechanical property of 1000 MPa hoop stress tolerance. We are carrying out the research and development of a 30 T all superconducting magnet immersed in liquid helium and a 23 T cryogen-free superconducting magnet, employing Y123 tape.