Patent ID: 7093449

Claim:
A two-stage hybrid cryocooler comprising: a first-stage Stirling expander comprising a first-stage regenerator having a first-stage-regenerator inlet and a first-stage-regenerator outlet; a second-stage pulse tube expander comprising a second-stage regenerator having a second-stage regenerator inlet in gaseous communication with the first-stage-regenerator outlet, and a second-stage regenerator outlet, a pulse tube having a pulse-tube inlet in gaseous communication with the second-stage regenerator outlet, and a pulse-tube outlet, wherein the second-stage regenerator and the pulse tube together provide a first gas-flow path between the first-stage regenerator and the pulse-tube outlet, a pulse tube pressure drop structure having a pulse-tube-pressure-drop inlet in gaseous communication with the pulse-tube outlet, and a pulse-tube-pressure-drop outlet, and a gas volume in gaseous communication with the pulse-tube pressure-drop outlet; and a gas flow shunt providing gaseous communication between a first-stage regenerator location at which a gas temperature is substantially the same as the gas temperature at the pulse-tube outlet and the pulse-tube outlet, wherein the gas flow shunt provides a second gas-flow path between the first-stage regenerator and the pulse-tube outlet.