| 摘要 |
PURPOSE:To obtain a water supply system requiring no forced circulation device for feeding of liquid nitrogen by a method wherein a cooling pipe arrangement, having the specific inside diameter, led out from a liquid nitrogen reservoir and provided by thermally connecting to a thermal shielding plate, is provided in a vacuum container. CONSTITUTION:Gravity is used as the driving force with which liquid nitrogen will be fet to a cooling pipe 4 in order to maintain a thermal shielding plate 3 at the temperature of liquid nitrogen. In this case, if the pipe has the inside diameter of about 15mm or more, the liquid nitrogen can be fed by the force of gravity without generation of vapor lock, and the thermal shielding plate 3 can be cooled sufficiently. Accordingly, a liquid nitrogen feeding system and a thermal shielding plate can be constituted with gravity as driving force using the pipe having the inside diameter of 15mm or more. Thus, the cooling piping is constituted in the pipe diameter of 15 to 20mm or thereabout so that the liquid nitrogen is sufficiently pervaded over the thermal shielding pipe and to accurately conduct the cooling of the thermal shielding plate, and as a result, the thermal shielding system can be constituted without occurrence of vapor lock and also without increase in size of the device. |
