Cooling method and energizing method of superconductor

摘要

A method is provided for cooling a high temperature superconductor such as an oxide superconductor to a lower temperature at a lower cost with a more simple system. A superconducting coil (2) is attached to a cooling stage (1a) of a refrigerator (1). By immersing the superconducting coil (2) on the cooling stage (1a) in liquid nitrogen (3), the superconducting coil (2) is cooled rapidly. Then, the superconducting coil (2) is further cooled by the refrigerator (1). By the cooling operation of the refrigerator (1), the liquid nitrogen (3) is solidified. Thus, the superconducting coil is surrounded with solidifed nitrogen (2). The superconducting coil (2) covered with the solidified nitrogen (3') is further cooled by the refrigerator (1). In the superconducting coil (2) cooled to a lower temperature and covered with solid nitrogen (3'), quenching is suppressed to allow a higher current to be conducted.