Cryogenic refrigerating method and apparatus

Claim 1

A CLOSED CRYOGENIC REFRIGERATING SYSTEM COMPRISING IN COMBINATION: (A) A FIXED MASS OF CRYOGEN CONTAINED WITHIN THE SAID CLOSED SYSTEM AND HAVING AN EXCLUSIVELY GASEOUS PHASE; (B) A COMPRESSOR FOR COMPRESSING SAID CRYOGEN, HAVING A LOW PRESSURE SAID AND A HIGH PRESSURE SIDE; (C) AT LEAST ONE TURBINE EXPANDER FOR EXTRACTING ENERGY FROM SAID CRYOGEN AND OPERABLE IN RESPONSE TO THE PRESSURE OF CRYOGEN COMPRESSED AT THE HIGH PRESSURE SIDE OF THE SAID COMPRESSOR AND EXHAUSTING EXPANDED CRYOGEN WITHN THE SYSTEM TO ESTABLISH THE COLDEST POINT WITHIN SAID SYSTEM; (D) CONDUIT MEANS, INCLUDING AT LEAST ONE COLD EXCHANGER, IN CONNECTIN BETWEEN SAID COMPRESSOR HIGH PRESSURE SIDE AND SAID EXPANDER FOR DELIVERING A COOLED COMPRESSED CRYOGEN TO SAID EXPANDER; (E) A PRESSURE MODULATING RESERVOIR IN CONNECTION WITH SAID EXPANDER AND ADAPTED TO RECEIVE SAID EXPANDED CRYOGEN AND RETAIN UNDER PRESSURE AN AMOUNT OF SAID CRYOGEN SUFFICIENT TO RESTRICT THE RATE OF EXPANSION OF POINT WITHIN SAID SYSTEM; (F) RETURN LOOP CONDUIT MEANS IN CONNECTION BETWEEN SAID EXPANDER AND SAID COMPRESSOR LOW PRESSURE SIDE, SAID RETURN LOOP CONDUIT MEANS RETURNING EXPANDED CRYOGEN TO RECOMPRESSION AND PROVIDING THERMAL EXCHANGE WITHIN SAID COLD EXCHANGER; AND (G) COLD SINK MEANS IN CONNECTION WITH SAID RETURN LOOP CONDUIT MEANS AND SITUATE INTERMEDIATE SAID EXPANDER AND SAID COLD EXCHANGER, FOR UTILIZING THE COLD PRODUCTION OF THE SYSTEM.