LIQUID HELIUM IS STORED IN THERMALLY-INSULATED DEWAR VESSEKS AT CRYOGENIC TEMPERATURES.

LIQUID HELIUM IS STORED IN THERMALLY-INSULATED DEWAR VESSEKS AT CRYOGENIC TEMPERATURES. NATURAL HEAT LEAK THROUGH THE WALLS OF THE DEWAR CAUSES SOME OF THE LIQUID TO BOIL OFF. THE COLD VAPOR MAY BE USED TO COOL THE SHIELDS OF THE DEWAR AND SOME MAY BE USED TO COOL APARATUS OR EQUIPMENT ADJACENT TO THE DEWAR. NEVERTHELESS, IT IS DIFFICULT TO RELATE THE COOLING GAS REQUIREMENTS WITH THE RATE OF LIQUID BOIL-OFF. A REFRIGERATOR CAPABLE OF RELIQUEFYING THE VAPOR IS THEREFORE REQUIRED. THIS PROJECT CONSISTS OF A RESEARCH AND DEVELOPMENT PROGRAM FOR A COMPACT, RELIABLE LOW-MAINTENANCE REFRIGERATOR CAPABLE OF RELIQUEFYING THE HELIUM BOIL-OFF VAPOR AND RETURNING IT TO THE CRYOGENIC DEWAR STORAGE VESSEL AND FOR PROVIDING SUPPLEMENTARY COOLING TO THE DEWAR SHIELDS. THE SYSTEM IS TRIPLE-FLUID LINDE-HAMPSON MACHINE WITH JOULE-THOMSON EXPANSIONS OF THE ARGON, NEON AND HELIUM WORKING FLUID. HELIUM BOIL-OFF VAPOR IS THE WORKING FLUID OF THE LOW-TEMPERATURE STAGE. NOVEL FEATURES OF THIS SYSTEM INCLUDE AN INTEGRAL THREE-FLUID, TWO-STAGE COMPRESSOR WITH HYDRAULIC DRIVE AND A HELIUM TURBO- EXPANDER TO ACHIEVE LOW HELIUM PRECOOLING TEMPERATURES AND TO ACHIEVE A PRESSURE BOOST TO THE HELIUM COMPRESSOR INPUT.