ALL-METAL, DEMOUNTABLE CRYOGENIC SEAL

IN MOST CRYOGENIC SYSTEMS, THE PIPING JOINTS IN COLD REGIONSOF THE SYSTEM ARE MADE BY WELDING OR SOLDERING. THIS IS ESSENTIAL BECAUSE EXISTING DESIGNS OF CRYOGENIC PIPE SEALS CANNOT BE RELIED ON NOT TO LEAK. ANY SUCH LEAKS INTO THE COLD BOX REDUCE THE EFFECTIVENESS OF THE INSULATION, THEREBY REDUCING THE EFFICIENCY OF THE REFRIGERATOR. WELDEDJOINTS MAKE REPLACEMENT OF COMPONENTS DIFFICULT AND HAVE THEADDED INCOVENIENCE OF SUBJECTING TO HIGH TEMPERATURES DELICATE COMPONENTS SUCH AS CRYOGENIC SENSORS OR MINIATURE TURBOEXPANDERS. SOLDERED JOINTS CAN BE MODE AT LOWER TEMPERATURES BUT REQUIRE THE USE OF FLUX WHICH MAY CONTAMINATE THE SYSTEM. HENCE THERE IS A NEED FOR A RELIABLE DEMOUNTABLE CRYOGENIC SEAL WHICH CAN WITHSTAND REPEATED CYCLING BETWEEN ROOM TEMPERATURE AND LIQUID HELIUM TEMPERATURES. THIS PROPOSAL DESCRIBES A NOVEL CONCEPT FOR SUCH A CRYOGENIC SEAL. THE ALL-METAL SEAL INCORPORATES THE PROVEN GOOD SEALING PROPERTIES OF SOFT METALS WITH A DESIGN THAT PREVENTS EXTRUSION OF THE SEALING AGENT. THE FEASIBILITY OF THE PROPOSED SEAL WILL BE DEMONSTRATED DURINGPHASE I BY A PROOF-OF-CONCEPT EXPERIMENT, AND IF PROVEN FEASIBLE, SUITABLE MANUFACTURING TECHNIQUES WILL BE DEVELOPED DURING THE PHASE II EFFORT.