| 摘要 |
PURPOSE:To shorten the cooling time of a superconducting coil from room temperature by installing a pipe, for preliminary cooling, which comes into contact with the superconducting coil and which can be cooled from the outside. CONSTITUTION:Helium gas which is supplied from a refrigerant generation device 17 enters a terminal box 13 through a pipe 19a, it then enters a superconductive coil, it is then returned to the refrigerant generation device 17 through a return pipe 19b, and this operation is repeated. A valve 26 to a refrigerant storage tank is closed until the temperature of the superconducting coil reaches about 20 K, a valve 25 for preliminary cooling is opened, and a coil conductor is cooled from the outside. When the temperature becomes 20 K or lower, the valve 25 for magnet preliminary cooling is closed, the valve 26 to the refrigerant storage tank is opened, liquid helium is stored in a liquid-helium storage tank 20, and a temperature rise due to creeping heat from a current lead and due to the leak of heat to the outside of supercritical- pressure helium is suppressed. When the temperature of the coil becomes a superconductive state, a current is applied from an exciting-current source 15, and the coil is excited. The temperature rise of the current lead during its excitation is suppressed by the liquid helium inside the liquid helium tank 20 and by the helium gas. |
