A double-inlet valve for a Gifford-McMahon (GM) type double-inlet pulse tube cryocooler system for providing cooling at cryogenic temperatures includes a fixed restrictor and a needle valve coupled to the fixed restrictor in parallel. The needle valve produces asymmetric flow. The combination of the fixed restrictor and the needle valve having an asymmetric flow provides improved alternating current (AC) flow characteristics and adjustability of direct current (DC) flow to increase the available cooling.

A cryogenic refrigerator system with heaters is constructed in modular form to serve as a portable servicing system to warm up and then cool down a target object by circulating a gaseous cryogen through a target object cryostat without moving the target object or breaking its vacuum. The main module is a refrigerator cryostat containing a fan that circulates gas through one or more heat exchangers which can warm or cool the gas by heaters and by one or more GM or Brayton cycle expanders. Additional components including one or more compressors, a gas charge and vent assembly, a control system, gas lines, power lines, and vacuum jacketed transfer lines can be assembled in the main module or additional modules. An example is a system that can be wheeled through a hospital to service a MRI cryostat.

A cryogenic refrigerator system with heaters is constructed in modular form to serve as a portable servicing system to warm up and then cool down a target object by circulating a gaseous cryogen through a target object cryostat without moving the target object or breaking its vacuum. The main module is a refrigerator cryostat containing a fan that circulates gas through one or more heat exchangers which can warm or cool the gas by heaters and by one or more GM or Brayton cycle expanders. Additional components including one or more compressors, a gas charge and vent assembly, a control system, gas lines, power lines, and vacuum jacketed transfer lines can be assembled in the main module or additional modules. An example is a system that can be wheeled through a hospital to service a MRI cryostat.

A thermo-acoustic device for transferring energy by an acoustic wave, includes a resonator; a source for generating the acoustic wave; a thermodynamic section that forms an acoustic network and includes a compliance volume, a thermo-acoustic core and a fluidic inertia. The thermodynamic section is situated between the resonator and the source. The thermo-acoustic core is within the thermodynamic section and includes a cold terminal, a hot terminal and a regenerator. The regenerator is positioned between the hot and cold terminals. The source includes a piston compressor. The compressor is arranged as a mechanical double acting reciprocating piston compressor with a first outlet for a pressure wave generated on one side of the piston and a second outlet for a pressure wave generated on the other side of the piston. The first outlet is coupled with a first thermodynamic section, and the second outlet coupled with a second thermodynamic section.

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 systemcryo-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 thermoacoustic heating device capable of effectively utilizing streaming, and including a prime mover in a first pipeline that forms a loop line, and a heating device in a second pipeline that forms another loop line. The first and second pipelines are connected to each other via a branch pipeline. A branch pipeline on the prime mover side and the second pipeline on the heating device side are positioned adjacent to each other, and a low-temperature side heat exchanger of the heating device is integrally formed with or held in contact with the branch pipeline on the prime mover side.

This disclosure describes systems, methods, and apparatus for improving the cooldown time, or efficiency of cooling systems, for a low-frequency one or multi-stage pulse-tube refrigerator. More specifically, actuation is performed on the driving frequency of the oscillating pressure and flow, on flow resistance of valves in the acoustic network that terminate the LF-OPTR or LF-DIPTR, and/or on the asymmetric flow resistance of the bypass valves in a LF-DIPTR's flow network. The actuation of these parameters is informed by measurements of the output pressure or output-input differential pressure at the steady flow compressor, the temperature of each stage of the refrigerator, and the temperature difference between the final stage and upper stages of the refrigerator, to name a few non-limiting examples.

A thermo-acoustic device for transferring energy by an acoustic wave, includes a resonator; a source for generating the acoustic wave; a thermodynamic section that forms an acoustic network and includes a compliance volume, a thermo-acoustic core and a fluidic inertia. The thermodynamic section is situated between the resonator and the source. The thermo-acoustic core is within the thermodynamic section and includes a cold terminal, a hot terminal and a regenerator. The regenerator is positioned between the hot and cold terminals. The source includes a piston compressor. The compressor is arranged as a mechanical double acting reciprocating piston compressor with a first outlet for a pressure wave generated on one side of the piston and a second outlet for a pressure wave generated on the other side of the piston. the first outlet is coupled with a first thermodynamic section, and the second outlet coupled with a second thermodynamic section.

In a pulse tube refrigerator, a gas flow passage is connected to a high-temperature end of a low-temperature side pulse tube and a compressor, such that a working gas flows in the gas flow passage. The gas flow passage includes: a first flow passage connected to the high-temperature end of the low-temperature side pulse tube; a second flow passage connected to the compressor and having an outlet facing an outlet of the first flow passage; and a housing that gastightly accommodates the outlet of the first flow passage and the outlet of the second flow passage. The housing has a gastight space communicating with the outlet of the first flow passage and the outlet of the second flow passage, the gastight space located on a side of the low-temperature side pulse tube with respect to the outlet of the first flow passage.

A first regenerator of a regenerative refrigerator includes a first regenerator member and a first cylinder accommodating the first regenerator member. A second regenerator includes a second regenerator member and a second cylinder accommodating the second regenerator member and may be connected to a low temperature end of the first regenerator. A gas pipe guides a coolant gas discharged from the first regenerator to a portion in the middle of the second regenerator. The gas pipe may include a plurality of gas relief holes in the middle of the gas pipe.