Stirling/pulse tube hybrid cryocooler with gas flow shunt

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 the first-stage regenerator inlet 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.

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 the first-stage regenerator 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, wherein the gas flow shunt comprises
• a biased-flow-resistance control structure, wherein a pressure drop through the gas flow shunt is larger when a working gas flows therethrough toward the pulse-tube outlet than when the working gas flows therethrough away from the pulse-tube outlet.

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, and wherein the first-stage regenerator inlet is maintained at an ambient temperature;
• 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, and wherein the pulse-tube outlet is maintained at ambient temperature,
• 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 the first-stage regenerator inlet 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.