| 摘要 |
PURPOSE:To easily enable a liquid circulation pump to be attachable and detachable by preparing valves onto a piping which makes the bottom of a liquid nitrogen container communicate with the sucking section for the liquid circulation pump and onto a piping which makes the discharge section for the liquid circulation pump communicate with the said piping. CONSTITUTION:A gas evaporating from a shield plate 10 passes through a piping 11 on the plate 10 and is led to the upper part of a liquid nitrogen container 6. When the nitrogen gas is brought into contact with a condensation surface 7a connecting thermally with a refrigerator 7 for liquid nitrogen, it is liquidified. At that time, valves 15 and 16 are still closed. The liquidified nitrogen 5 is supplied from the container 6 to a piping 11a through a liquid circulation pump 9 after valves 19, 20 and 21 are opened, and to the piping 11 on the plate 10 thereafter. The nitrogen gas generating from the plate 10 or liquid is returned to the container 6 for further circulation. In case where the pump 9 generates any trouble, the pump 9 can be exchanged while the plate 10 remains cooled. |
