| 摘要 |
PROBLEM TO BE SOLVED: To shorten a cooling period of time, and expand a contact area to transmit cold, and in addition, improve the cooling capability by providing a refrigerant gas valve which performs the putting in/taking out of a refrigerant gas based on a detected temperature of a temperature sensor. SOLUTION: When a temperature sensor 24 detects a temperature which is not more than a specified temperature being set in a control device 25, the control device 25 closes gate valves 15 and 16. By this motion, the feeding of a helium gas to a first stage cold head section F-1 is stopped. Then, the process is transferred to a motion temperature cooling stage wherein the cooling of a superconductive coil is performed by a second stage cold head section F-2 alone, and the superconductive coil 10 under an extremely low temperature state is obtained. At the time of a transfer to the motion temperature cooling stage, the helium gas may be discharged so that the gas may not remain in a cooling pipe 14. Also, by totally closing the gate valves 15 and 16 under a closed state after the completion of a preliminary cooling stage, the cooling pipe 14 is prevented from being clogged with frost or ice due to the entering of moisture or the like in air. |
