Superconducting electromagnet device, cooling method therefor, and magnetic resonance imaging device

A cooling method for a superconducting electromagnet device including:

• a refrigerant circulation flowpath in which a refrigerant circulates;
• a refrigerator for cooling vapor of the refrigerant in the refrigerant circulation flowpath;
• a superconducting coil cooled by the circulating refrigerant;
• a protective resistor that is connected in parallel with the superconducting coil;
• and
• a vacuum insulating container for at least accommodating the refrigerant circulation flowpath, the superconducting coil, and the protective resistor, wherein
• the protective resistor is formed to thermally contact the superconducting coil and have an internal space that includes a flowpath connected to the outside,
• during initial cooling,
• a high-boiling-point refrigerant that has a higher boiling point than the refrigerant and is frozen by the refrigerant is supplied to the internal space from the flowpath connected to the outside, and the high-boiling-point refrigerant is further supplied to the refrigerant circulation flowpath to cool a superconducting magnet, and
• after the initial cooling,
• the superconducting magnet is cooled by supplying the refrigerant after the low-boiling-point refrigerant is removed from the refrigerant circulation flowpath, and the high-boiling-point refrigerant that remains in the internal space is frozen.