| 摘要 |
PURPOSE:To attain efficient cooling from pre-cooling to cooling for cryogenic temperature maintenance, by adequately changing the flow passage of a cooling pipe where a refrigerant flows by a valve device. CONSTITUTION:Superconductor 11 from a superconductive magnet penetrating cooling pipes 12a to 12d. During the cooling of this magnet, bypass valves 14a to 14c are closed and supply valves 16a to 16c, and discharge valves 18a to 18c are opened, ao that a refrigerant supplied from the compressor will flow through cooling pipes 12a to 12d in parallel. As a result, the diameter of the refrigerant passage increases equivalently and the passage length shortens, causing the reduction in pressure loss. Therefore, the pre-cooling time can be shortened. After the pre- cooling, valves 14a to 14c are opened and valves 16a to 16c, and 18a to 18c are closed to flow the refrigerant through pipes 12a to 12d in series. Consequently, a constant volume of the refrigerant can be flowed through a long passage, and cooling performance also improves. |
