Integral linear cryogenic Stirling refrigerator comprised of the free piston positive displacement pressure wave generator, the moving assembly of which is connected to the free piston displacer by the dynamic “spring-mass-spring” mechanical phase shifter the mechanical properties of which (spring rates and weight) are selected to provide a predetermined phase lag of motion of the displacer piston relative to the moving assembly of pressure wave generator.

A thermoacoustic stack includes an outer wall which is cylindrical and has a length extending between a first end and a second end. An internal wall structure is disposed inside the outer wall. The internal wall structure includes a plurality of spaced adjacent wall surfaces extending along the length of the outer wall to provide open flow passages between the spaced adjacent wall surfaces. A first cross member extends across the outer wall at the first end and is connected to the outer wall and the internal wall structure at the first end.

A chuck includes a chuck surface, a plurality of vacuum ports being distributed over the chuck surface. Each of the vacuum ports is open to a conduit that is connectable to a suction source that is operable to apply suction to that vacuum port. A flow restrictor is located within each conduit and is characterized by a flow resistance. The flow resistance of the flow restrictor in at least one conduit is less than the flow resistance of the flow restrictor in at least one other conduit.

An expander unit of a cryogenic refrigerator device includes a moving assembly with a porous regenerative heat exchanger configured to move back and forth along a longitudinal axis. A magnetic spring assembly includes a stationary magnetic assembly fixed to the cold finger base that includes one or more magnetic rings fixedly arranged about a bore. A movable magnetic assembly includes one or more movable magnetic rings fixed to the moving assembly. An outer lateral dimension of each of the movable magnetic rings is less than an inner lateral dimension of the bore. The stationary magnetic assembly and the movable magnetic assembly are configured such that, when the moving assembly is displaced along the longitudinal axis from an equilibrium position, attractive and repulsive forces between the movable magnetic assembly and the stationary magnetic assembly yield a restoring force that is directed to restore the moving assembly to the equilibrium position.

A thermoacoustic refrigeration assembly includes a resonating tube having a first end and a second end; a first mechanical oscillator at the first end; a second mechanical oscillator at the second end; and a thermoacoustic stack sandwich disposed along a length of the resonating tube through which gas travels. The stack sandwich includes a first outboard heat exchanger on a first side of the stack sandwich facing the first mechanical oscillator, a second outboard heat exchanger on a second side of the stack sandwich facing the second mechanical oscillator, and a center heat exchanger disposed between the first outboard heat exchanger and the second outboard heat exchanger.

A pneumatically driven cryogenic refrigerator operating primarily on the Gifford-McMahon (GM) cycle is switched from cooling to heating by a switch valve between a rotary valve and a drive piston that causes the displacer to reciprocate. The rotary valve has ports at two radii, one that cycles flow to the displacer and a second that cycles flow to the drive piston. Two ports cycle flow to the top of the drive piston, the “cooling” port optimizes the cooling cycle and the “heating” port provides a good heating cycle. A switch valve that changes the flow from one port to the other can be linearly or rotary actuated. The rotary valve does not reverse direction.

A first-stage regenerator material and a second-stage regenerator material are regenerator materials each having a laminated structure for use in a GM refrigerator. Each layer of the regenerator material is provided with a plurality of holes to allow gas to pass therethrough along a laminating direction. At least one layer includes a base material and a coating covering the base material. Volumetric specific heat of the coating is larger than volumetric specific heat of the base material in a temperature range from 20 K to 40 K.

This invention provides a regenerator material having a high specific heat, particularly in the temperature range of 10 to 25K, and a regenerator and a refrigerator comprising the regenerator material. The present invention specifically provides an HoCu-based regenerator material represented by general formula (1): HoCu.sub.2-xM.sub.x (1), wherein x is 0<x≤1, and M is at least one member selected from the group consisting of Al and transition metal elements (excluding Cu), as well as a regenerator and a refrigerator comprising the regenerator material.

A cryocooler includes a cold head including a displacer movable in an axial direction, a drive piston connected to the displacer to move the displacer in the axial direction, an expansion chamber formed with the displacer, a piston drive chamber formed with the drive piston, a spool valve including a valve drive chamber, a spool that moves between a first position and a second position in response to a pressure of the valve drive chamber, and a pressure control mechanism configured to control a pressure of the valve drive chamber so that the spool reciprocates between the first position and the second position, and to generate a pressure fluctuation having an opposite phase to the pressure fluctuation in the expansion chamber in the piston drive chamber in synchronization with the reciprocation of the spool.

A method may produce a heat regenerating material particle, including: preparing a slurry by adding a powder of the heat regenerating substance to an alginic acid aqueous solution and mixing the powder of the heat regenerating substance and the aqueous alginic acid solution; and forming a particle by gelling the slurry by dropping the slurry into a gelling solution. The gelling solution may include a metal element including calcium (Ca), manganese (Mn), magnesium (Mg) beryllium (Be), strontium (Sr), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), and cobalt (Co). The forming may involve controlling the gelation time so that a concentration of the metal element in a first region of the particle becomes lower than a concentration of the metal element in a second region. The second region may be closer to an outer edge of the particle compared to the first region.