METHOD AND APPARATUS FOR PRECOOLING A MASS PRIOR TO IMMERSION IN A CRYOGENIC LIQUID

摘要

An apparatus and method for precooling a mass to be cooled to a final low temperature by immersion in a cryogenic liquid, e.g. liquefied helium. The gaseous phase of the cryogenic liquid is cooled by heat exchange with a cryogeni c liquid having a higher boiling point than the cryogenic liquid within which the mass is to be immersed. The cooled gaseous phase is circulated through a vessel containing the mass, recovered, recooled and recirculated until the mass and its containment vessel are at the desired precooling temperature. Thereafter cryogen ic liquid can be introduced into the vessel to immerse the mass.