Cryogenic pump for a refrigerator system

Claim 1

A COLD TRAP SYSTEM COMPRISING A FLASK ENCLOSING LIQUEFIED GAS UNDER PRESSURE, SIPHON MEANS EXTRUDING INTO THE LIQUEFIED GAS IN SAID FLASK FOR EXPELLING FROM SAID FLASK LIQUEFIED GAS, CONDUIT MEANS IN COMMUNICATION WITH THE PRESSURIZED GAS IN SAID FLASK, CONTROL VALVE MEANS CONNECTED WITH SAID CONDUIT MEANS ADAPTED TO RELEASE PRESSURIZED GAS FROM SAID FLASK, AND RENDER SAID SIPHON MEANS INOPERATIVE, A COLD TRAP EVAPORATOR DEFINING AN ENCLOSED CHAMBER ADAPTED TO BE MAINTAINED CONTINUOUSLY AT A MAXIMUM LEVEL OF LIQUEFIED GAS, TUBULAR MEANS FOR CONDUCTING THE LIQUEFIED GAS FROM SAID SIPHON MEANS TO SAID COLD TRAP EVAPORATOR UPON SHUTTING OFF OF SAID CONTROL VALVE, AN OVERFLOW PIPE IN SAID EVAPORATOR FOR CONDUCTING FROM THE TOP OF SAID EVAPORATOR A FLUID DISCHARGE, TEMPERATURE SENSITIVE MEANS LOCATED TO RECEIVE THE FLUID DISCHARGE AND CONNECTED TO SAID CONTROL VALVE MEANS FOR SHUTTING OFF SAID VALVE MEANS UPON RECEIVING PRESSURIZED GAS AND FOR OPENING SAID VALVE UPON RECEIVING LIQUEFIED GAS.