A cryogenic cooling system includes a gas circulation source; a cryocooler that cools a cooling gas; a cooling gas flow path that causes a cooling gas to flow from the gas circulation source to the object to be cooled; and a control device that controls the gas circulation source so as to execute initial cooling of the object to be cooled according to a prescribed flow rate pattern. The prescribed flow rate pattern is predetermined such that the cooling gas flows through the cooling gas flow path at a first average flow rate, and the cooling gas flows through the cooling gas flow path at a second average flow rate. The second average flow rate is smaller than the first average flow rate such that the cooling capacity of the cryogenic cooling system is increased.

An acoustic wave generation unit oscillates working fluid of 35 atm or less so as to generate acoustic waves with a frequency in a range from 50 Hz or more and 500 Hz or less. A heat/acoustic wave conversion component has a partition wall of 5.0 W/mK or less between two end faces which defines a plurality of cells of 620 cells/cm.sup.2 or more and 3100 cells/cm.sup.2 or less. A heat exchanger disposed close to one end face receives heat from a first external air flowing into the heat exchanger and gives the heat to the one end face so as to flow out a cold air. Another heat exchanger disposed close to the other end face receives heat from the other end face and gives the heat to a second external air flowing into the another heat exchanger so as to flow out a warm air.

A pulse tube cryocooler includes a pulse tube that includes a tube inner space, and an integral flow straightener that includes a flow straightening layer disposed to face the tube inner space so as to straighten a refrigerant gas flow from the tube inner space or into the tube inner space and a heat exchange layer formed integrally with the flow straightening layer outside the flow straightening layer with respect to the tube inner space so as to exchange heat with the refrigerant gas flow by contact with the refrigerant gas flow and is disposed at a low-temperature end and/or a high-temperature end of the pulse tube. The flow straightening layer includes a plurality of protrusions that protrude from the heat exchange layer toward the tube inner space.

A compact, low power cryo-cooler for cryogenic systems capable of cooling gas to at least as low as 2.5 K. The cryo-cooler has a room temperature compressor followed by filtration. Within the cryostat, four counterflow heat exchangers precool the incoming high-pressure gas using the outflowing low-pressure gas. The three warmest heat exchangers are successively heat sunk to three stages of a pulse tube to absorb residual heat from the slight ineffectiveness of the heat exchangers. The pulse tube cold head also absorbs loads from instrumentation leads and radiation loads. The pulse tube stages operate at around 80 K, 25 K, and 10 K. The entire system—cryo-cooler, drive and control electronics, and detector instrumentation, fits in a standard electronics rack mount enclosure, and requires around 300 W or less of power.

A pulse tube cryocooler includes a pulse tube; a bidirectional flow path that is connected to the pulse tube, and through which a pulse tube inflow and a pulse tube outflow alternately flow; a DC flow generator that is disposed in the bidirectional flow path, causes a first pressure drop in the pulse tube inflow, and causes a second pressure drop different from the first pressure drop in the pulse tube outflow; and a flow rate regulator that is disposed in the bidirectional flow path in series with the DC flow generator, and adjusts flow rates of the pulse tube inflow and the pulse tube outflow.

Systems and methods of continuous cooling at cryogenic temperatures. One exemplary aspect involves a refrigeration system that includes: a chamber adapted to hold liquid and gaseous coolant received from a cooling pot; a first adsorption pump having an inlet end in fluid communication with the chamber, the first adsorption pump configured to capture gas from the liquid and gaseous coolant when the first adsorption pump is enabled; a second adsorption pump having an inlet end in fluid communication with the chamber, the second adsorption pump configured to capture gas from the liquid and gaseous coolant when the second adsorption pump is enabled; a means for desorbing the gas captured by the first adsorption pump; and a means for desorbing the gas captured by the second adsorption pump.

A circulating loop for transporting refrigeration to a remote location is connected serially between a Gifford-McMahon (GM) or GM type Pulse Tube cold head and the compressor. Either high pressure gas from the compressor can flow through the remote heat station before returning to the cold head or low pressure gas can flow from the cold head to the remote heat station before returning to the compressor. A first fraction of gas, which may include all of the gas at ambient temperature, enters a counter-flow heat exchanger, is cooled by the cold head, flows to the remote load, and then returns to ambient temperature as it flows through the counter-flow heat exchanger. The high or low pressure line may have a circulation control valve that diverts a second fraction of gas to flow directly between the cold head and compressor. A controller adjusts the circulation control valve to optimize the cooling of the load.

A cryogenic cooling system is provided comprising: a cooled plate (2) thermally coupled to a cryogenic refrigerator (9), a heat switch assembly and a target assembly (5). The target assembly (5) comprises a target refrigerator (12) configured to obtain a lower base temperature than the cryogenic refrigerator (9). The heat switch assembly (18) comprises one or more gas gap heat switches, the heat switch assembly (18) having a first end thermally coupled to the cooled plate (2) and a second end thermally coupled to the target assembly (5). A sorption pump (22) is provided for controlling the thermal conductivity across the heat switch assembly (18) in accordance with the temperature of the sorption pump (22) The sorption pump (22) is thermally coupled to the cryogenic refrigerator (9), by a thermal link (46) extending from the cooled plate (2) to the heat switch assembly (18). The sorption pump (22) is arranged at a position along the thermal link (46) between the heat switch assembly 18 and the cooled plate (2).

A cryogenic cooling system is provided comprising a primary insert (118) and a demountable secondary insert (128). The primary insert (118) comprises a plurality of primary plates (111, 112), each primary plate having a primary contact surface, and one or more primary connecting members (117) arranged so as to connect the plurality of primary plates (111, 112). The demountable secondary insert (128) comprises a plurality of secondary plates (121, 122), each secondary plate having a secondary contact surface, and one or more secondary connecting members (127) arranged so as to connect the plurality of secondary plates (121, 122) such that the secondary insert (128) is self-supporting. One or more adjustment members are configured such that, when the secondary insert (128) is mounted to the primary insert (118), the adjustment members cause the primary and secondary contact surfaces of the respective primary (111, 112) and secondary plates (121, 122) to be brought into conductive thermal contact.

The object of this invention is to increase the life of the displacer and stem seals of the reciprocating displacer of a Gifford McMahon (GM) cryogenic expander. The seal comprises a ring that is relatively long and thin and uses the pressure difference across the seal, acting behind the ring, as the primary force to bring the ring into contact with the cylinder and stem walls. The pressure difference across the seal ring pushes the ring to one end of the groove, and the friction force pushes the ring in the same direction while it is moving. The sealing force is distributed over a larger area compared with a conventional backed “O” ring thus reducing the wear rate and increasing the seal life.