Method for preparing a subcooled liquid nitrogen under an atmospheric pressure condition using vacuum pump and heat conduction characteristic

摘要

PURPOSE: A method for preparing subcooled liquid nitrogen under atmospheric pressure condition by using vacuum pump and heat conduction characteristic is provided, which is useful in such fields as cryogenic storage and high temperature superconductivity where subcooled liquid nitrogen is used as a coolant. CONSTITUTION: Air is pumped out from a vacuum region(34) at a pressure of less than 10¬-3 torr, and then liquid nitrogen(36) is introduced into both an inner container(14) and an outer container(12). After a liquid nitrogen valve is closed, air is pumped out from the outer container with a vacuum pump. As air is pumped out from the outer container, the liquid nitrogen is cooled, and accordingly the liquid nitrogen(36') contained in the inner container is cooled by heat conduction.