Upgrade Plan on NIFS Superconducting Magnet Test Facility

In 1991, the superconducting magnet test facility had been constructed in National Institute for Fusion Science. The facility consists of a helium liquefier/refrigerator with the cooling capacity of 600 W at 4.5 K, large cryostats, a mechanical testing machine, DC power supplies with the maximum current of 75 kA and a distributed control system. So far, the development of the superconducting coils for the Large Helical Device had been conducted and many collaborative works have been carried out. However, the test facility with higher bias filed is needed to develop superconducting coils for fusion reactors and the cooling system, which can supply coolant of various temperature to test samples, is required to apply HTS to large-scale conductors. Therefore, the test facility will be upgraded to promote the development of superconducting coils for fusion reactors. The maximum bias field will be upgraded from 9 T to 15 T to investigate the performance of superconductors under the higher bias field and the existing helium liquefier/refrigerator will be replaced with a variable temperature one to test those under various temperature environment. Consequently, it is expected to progress the development of the superconductors for fusion reactors and the development of large-scale HTS conductors.