Abstract: A highly efficient motor driver circuit of an electronic controller for linear cryogenic coolers operates directly from a variable power supply, such as a battery, without the need for the voltage regulator control circuit of the prior art. Elimination of the prior art voltage regulator ensures a higher efficiency motor driver circuit of the electronic controller. Both open-loop and closed-loop controllers electronically control the motor driver circuit. The open-loop controller protects against temperature sensor failure, and will limit maximum motor power as a function of system ambient temperature. The closed-loop controller regulates the temperature of the cold finger accurately to a preset value, using feedback from a temperature sensor along with a novel pulse-width modulation concept for modifying motor drive waveforms.

Abstract: A microminiature Stirling cycle engine or cooler is formed utilizing semiconductor, planar processing techniques. Such a Stirling cycle thermomechanical transducer has silicon end plates and an intermediate regenerator. The end plates are formed with diaphragms and backspaces, one end plate forming the expansion end and the opposite end plate forming the compression end, with the regenerator bonded in between. A control circuit apparatus is linked to the diaphragms for controlling the amplitude, phase and frequency of their deflections. The control circuit apparatus is adapted to operate the transducer above 500 Hz and the passages and the workspace, including those within the regenerator, expansion space and compression space, are sufficiently narrow to provide a characteristic Wolmersley number, which is characteristic of the irreversibilities generated by the oscillating flow of the working fluid in the workspace, below substantially 5 at the operating frequency above 500 Hz.

Abstract: Herein disclosed is a regenerative heat exchanger comprising a cylindrical core casing and a stack body core formed by a plurality of circular mesh plates each having fluid passage holes and stacked on one another to form fluid passageways. The stack body core is housed in the core casing to have a fluid cooling medium introduced into the fluid passageways to carry out heat exchange between the stack body core and the fluid cooling medium. Each of the mesh plates has on its outer periphery a reference mark portion positioned with respect to the fluid passage holes, and the mesh plates collectively form a row of reference mark portions indicative of the form of each of the fluid passageways. The row of reference mark portions enables to easily modify or adjust the shapes of the fluid passageways of the stack body core by relatively rotating the mesh plates with reference to the reference mark portions.

Abstract: Active magnetic regenerator and method using Gd.sub.5 (Si.sub.x Ge.sub.1-x).sub.4, where x is equal to or less than 0.5, as a magnetic refrigerant that exhibits a reversible ferromagnetic/antiferromagnetic or ferromagnetic-II/ferromagnetic-I first order phase transition and extraordinary magneto-thermal properties, such as a giant magnetocaloric effect, that renders the refrigerant more efficient and useful than existing magnetic refrigerants for commercialization of magnetic regenerators. The reversible first order phase transition is tunable from approximately 30 K to approximately 290 K (near room temperature) and above by compositional adjustments. The active magnetic regenerator and method can function for refrigerating, air conditioning, and liquefying low temperature cryogens with significantly improved efficiency and operating temperature range from approximately 10 K to 300 K and above. Also an active magnetic regenerator and method using Gd.sub.5 (Si.sub.x Ge.sub.1-x).sub.

Abstract: A free piston Vuillermier machine which is an external combustion heat machine using a regenerative cycle, wherein a low-temperature displacer is made hollow to form a low-temperature displacer gas spring chamber, a low-temperature displacer rod is made hollow to form a hollow chamber for accommodating a high-temperature displacer rod therein as well as a high-temperature displacer gas spring chamber. Further, in the above configuration, a gas spring chamber passage may be formed to make the high-temperature displacer gas spring chamber communicate with the low-temperature displacer gas spring chamber. A high-temperature displacer mechanical spring may be provided in the high-temperature displacer gas spring chamber, and a low-temperature displacer mechanical spring mounted on the low-temperature displacer rod may be provided in the low-temperature displacer gas spring chamber.

Abstract: The weight of crank mechanism portion is reduced and driving force efficiency is improved by reducing in the friction loss in the driving force on the side of a compression piston. A gas compressor expander includes a first expansion cylinder and a first displacer arranged in a T shape, a first connecting lever, a first compression cylinder, a first compression piston, a second expansion cylinder and a second displacer also arranged in a T shape, a second connecting lever, a second compression cylinder, a second compression piston. A first expansion chamber, a first compression chamber, and a third compression chamber are communicated through a first communicating tube, while a second expansion chamber, a second compression chamber, and a fourth compression chamber are communicated through a second communicating tube.

Abstract: A cryogenic cooling apparatus (cryocooler) with voltage isolation includes a cold end structure, which may be placed in thermally and electrically conductive contact with an electrically charged structured to be cooled, a warm end, and an electrically insulating structure between the warm end and the cold end structure of the apparatus so as to electrically isolate the cold end structure from the warm end. Two cold fingers, each comprising a cold end structure, a warm end, and the insulating structure, may be conveniently combined into a single cooling apparatus for the cooling of two electrically charged structures at different voltage levels, e.g., conductive electrical leads to a cryogenic superconductive energy storage device. The electrically insulating structure is selected so as to provide both electrical isolation and to contain a cryogenic working fluid within the cold finger of the cryocooler.

Abstract: A drive for driving a displacer in a cryogenic refrigerator includes a rotatable cam having a cam surface. The cam is rotatable about a pivot point with a cam follower contacting the cam surface. Rotational motion of the cam is converted into reciprocating motion of the cam follower. A displacer rod is coupled between the cam follower and the displacer for transferring the reciprocating motion of the cam follower to the displacer for driving the displacer.

Abstract: A bi-directional Joule-Thomson device comprising two nearly identical heating containers which are connected via tubing to a cooling head. The cooling head is contained within a low temperature vacuum cryostat. Each of the small diameter tubes enters a chamber in the body of the cooling head. The chambers are connected by a small diameter orifice. Heat exchangers at ambient temperature and/or thermoelectric devices are used to cause the temperature of the gases entering and leaving the heating containers and cryostat to be at or near ambient. Within the cryostat, the small diameter tubes are thermally connected so that the cold gas flowing outward will cool the hotter incoming gas. The power for operation is supplied through two heating elements (one in each of the nearly identical heating vessels). This device will continue to perform at reduced power even if one of the heating elements fails.

Abstract: A regenerative type engine which improves efficiency is provided. The regenerative type engine with fluid control mechanism comprises a radiator arranged in a position which is at least one of between the pressure fluctuation source and a regenerator and between a cold head and a phase regulating mechanism, and a flow path controller connected to the radiator, for independently regulating the flow path in the forward process and the flow path in the backward process of the operating fluid within the system of the regenerative type engine, the flow path controller independently regulating the flow path in the forward process and the flow path in the backward process such that the flow path in the forward process passes through the radiator and the flow path in the backward process bypasses the radiator.

Abstract: A heating and cooling machine, operating according to a regenerative gas cycle process with a working medium, has a pressure-tight housing and a heat source connected inside the housing. Two linearly moveable pistons are positioned inside the housing. The two pistons delimit therebetween a warm working volume and are driveable by a control unit. The first piston together with the housing delimits a hot working volume loaded with heat from the heat source. The second piston together with the housing delimits a cold working volume. Regenerators as well as a warm heat transfer element and a cold heat transfer element are positioned in the housing. The three working volumes communicate with one another through the regenerators and the warm and cold heat transfer elements. A partition for transmitting heat energy generated by the heat source to the hot working volume, has the shape of a radially symmetrical dome and is connected to the housing so as to be heat-insulated relative to the housing.

Abstract: A multistage type tube refrigerator comprising a regenerator-side pressure oscillation generator, first regenerator connected to the regenerator-side pressure oscillation generator, first cold head connected to the low temperature side of the first regenerator, a first pulse tube having one end connected to the first cold head and the other end connected by way of a first flow regulating mechanism to a first pulse tube-side phase shifter, second regenerator having one end connected to the first cold head and the other end connected to the second cold head, a second pulse having one end connected to the second cold head and the other end connected to second pulse tube-side phase shifter by way of second flow regulating mechanism, in which the first pulse tube-side phase shifter and the second pulse tube-side phase shifter are controlled independently of each other. Further, the pulse tube refrigerator operated while setting the phase angle of the pulse tube-side phase shifter to -50.degree. to -120.degree.

Abstract: A superconducting magnet apparatus comprises a superconducting coil unit, and a refrigerant-filled chamber type refrigerator having a plurality of cooling stages. At least a final cooling stage of the cooling stages includes a static-type refrigerant-filled chamber and is associated with the superconducting coil unit, and at least a first cooling stage of the cooling stages includes a movable-type refrigerant-filled chamber.

Abstract: An indium gasket having a configuration which allows the indium to reach its yield point at a relatively low contact pressure. The indium gasket is provided with a multiplicity of openings which are filled by the deforming indium during compression between the cryocooler and the cryocooler interface sleeve of a superconducting magnet system. The creation of openings in the gasket has the effect of decreasing the mechanical interface pressure at which the indium yields. The indium flows at a mechanical interface pressure that does not exceed the structural strength requirements of the cryocooler. The indium flows into the empty spaces formed by the openings, thereby providing the necessary thermal conductance between the cryocooler and the interface sleeve. The result is a relatively small temperature difference between the interface sleeve and the cryocooler during cooling of the superconducting magnets.

Abstract: To improve cooling efficiency of a pulse tube refrigerator, it is found that creating two conditions in the refrigerator, particularly in a regenerator is effective. In a first condition, working fluid in the regenerator should be compressed or expanded without having any displacement thereof, while it should be displaced without compression or expansion in a second condition. In order to realize this idea, a fluid displacement control valve assembly including two relief valves is disposed between a pulse tube and a buffer tank. Each of the relief valves is a normally closed one-way valve, and the valves open in opposite directions to one another when a pressure difference between the pulse tube and the buffer tank reaches a predetermined value, thus allowing the working fluid to be displaced after its compression from the pulse tube to the buffer tank and after its expansion from the buffer tank to the pulse tube.

Abstract: A cryogenic refrigerator which is capable of preventing a deterioration in refrigerating performance and which has high efficiency includes: a first compressor; a first expander having at least one accumulator using an accumulating material comprising a rare earth alloy or compound which has a large specific weight at 10K or below or an accumulating material comprising helium; a sub-expansion space which effects further expansion of a working fluid introduced thereto from an expansion space of the first expander; and a second compressor which compresses the working fluid returning from the sub-expansion space.

Abstract: A synchronous twin reciprocating piston apparatus includes a cylinder and a number of stator assemblies mounted in fixed relation thereto. The stator assemblies are constructed so as to generate a radial magnetic field in a number of regions near to each end of the cylinder. The apparatus also includes a pair of piston-magnet assemblies, each having a piston slidable within an end of the cylinder, and a number of compound permanent magnet systems located within the regions. Each compound permanent magnet system includes a first section magnetized in a direction radial relative to the cylinder axis and a second section, axially displaced from the first, magnetized in the opposite direction. When the stator assemblies are excited with an alternating current, the piston-magnet assemblies reciprocate axially relative to said cylinder, and synchronously with the frequency of the applied current. The pistons then generate a pulsating pressure within the cylinder.

Abstract: To improve refrigerating efficiency by preventing working fluid flowing into a pulse tube from a high-temperature end side thereof from reaching a cooling part in a cryogenic refrigerator, a ball-shaped travel member which has almost the same cross-section as the cross section of the pulse tube is inserted into the pulse tube and moves together with the working fluid therein. In this arrangement, when the working fluid begins to flow into the pulse tube from a flow rate regulation part on the high-temperature end side of the pulse tube, the travel member located within the pulse tube moves toward a cooling part together with the working fluid flowing in the pulse tube. Since the travel member has almost the same cross-section as the cross-section of the pulse tube, there is no possibility that the working fluid flows through between the inner wall of the pulse tube and the travel member.

Abstract: An expander for a concentric pulse tube cooler. The inventive expander includes a central pulse tube; a concentric insulation tube disposed around the central pulse tube, the insulation tube having a concentric chamber therein and the chamber being filled with an insulator and the insulator being atmospheric; and a regenerator disposed around the concentric insulation tube. In a particular implementation, the insulator tube includes a vent which allows the insulation chamber to communicate with the surrounding atmosphere. When used in space, the chamber is filled with a void and the insulator becomes a vacuum and provides effective insulation at cryogenic temperatures.

Abstract: A three state EM motor/damper used in a ground-based or space-based Stirling refrigerator expander mechanism provides multiple states of operation to obtain fail safe performance during assembly, launch (space based refrigerators), and operation. The device is attached to the expander's reciprocating displacer to enable actuation during assembly, provide maximum damping during launch, and provide attenuated damping to control displacer motion during operation as a refrigerator. The motor/damper is a linearly actuated "voice coil" device employing a moving coil wound on an electrically conductive bobbin and oscillating within a permanent magnet/back iron field assembly. The electrically conductive bobbin internally generates and dissipates eddy currents when moved through the magnetic field. The bobbin acts as a coil of one turn, shorted to itself. This mechanism transforms kinetic energy to electrical energy, which then dissipates as heat. In this manner, mechanical energy is removed from the system.

Abstract: A heat exchanger wherein the media that take part in the heat transfer are separated from one another. To provide a compact heat exchanger that has a high efficiency, the heat exchanger is formed by a base body, one surface of which is provided with at least one groove that extends from the inlet to the outlet and that is sealed by a cover, in the form of a flow channel, for the heat-absorbing heat transfer medium. The other surface of the base body has a plurality of channels and/or pores for the heat-emitting medium.

Abstract: A thermoacoustic device having a thermal stack made from a piece of porous material which provides a desirable ratio of thermoacoustic area to viscous area, which has a low resistance to flow, which minimizes acoustic streaming and which has a high specific heat and low thermal conductivity is disclosed. The thermal stack is easy and cheap to form and it can be formed in small sizes. Specifically, in one embodiment, a thermal stack which is formed by the natural structure of a porous material such as reticulated vitreous carbon is disclosed. The thermal stack is formed by machining a block of reticulated vitreous carbon into the required shape of the thermal stack. In a second embodiment, a micro-thermoacoustic device is disclosed which includes a thermal stack made of a piece of porous material such as reticulated vitreous carbon. In another embodiment, a heat exchanger is disclosed which is formed of a block of heat conductive open cell foam material.

Abstract: A heat pump type air conditioner having a heat gas engine having a radiator and a cooler, an outdoor heat exchanger provided in an outdoor unit and an indoor heat exchanger provided in an indoor unit, is further provided with a heat exchanger in the outdoor unit and/or the indoor unit, and control means for controlling water flow in first and second passages so as to perform cooling/heating operation. When slightly-heating or slightly-cooling dry operation or defrosting operation is required, a part of the hot water from the radiator is allowed to selectively flow through the second fluid passage into the heat exchanger by adjusting opening degree of open/close valves disposed between the first and second fluid passages.

Abstract: A self-cooling Stirling cycle cooler (1). The cooler (1) includes a conduit (20) for transporting thermal energy from a first location to a second location. The conduit is a closed loop having first and second ends terminating in a first chamber (29). A pump (14) is mounted in the first chamber (29) for moving the heat energy therein from the first location to the second location. The pump (14) includes a piston (40) which reciprocates in the first chamber (29). A first valve (42) is provided for controlling the direction of a flow of fluid in the conduit (20) into the first chamber (29) and a second valve (46) for controlling the flow of the fluid in the conduit (20) out of the first chamber (29). In a Stirling cycle cooler, the balancer mass is used as the pump piston to facilitate the movement of fluid in the conduit. By utilizing the balancer mass of a Stirling cycle cooler, self-cooling is effected with minimal additional hardware, weight and cost.

Abstract: A cryocooler system (20) includes a heat sink (24), such as a Stirling cycle heat engine having a cold cylinder sleeve (26) and a cold gas pocket region (32) within the cold cylinder sleeve (26). An adapter (36) is sealed to the cold cylinder sleeve (26) with a hermetic seal, such as a welded joint (38). A copper cold tip (28) has a first end (34) directly contacting the cold gas pocket region (32) within the cold cylinder sleeve (26). The periphery of the cold tip (28) is welded, preferably by frictional welding, to the adapter (36). The cold tip (28) thereby provides a hermetic seal to the end of the cold cylinder sleeve (26) to retain the working gas within the cold gas pocket region (32) and also to provide an unimpeded heat flow path to the cold gas pocket region (32).

Abstract: A cooling apparatus comprises a main refrigerator having a refrigerant-filled chamber, a sub-refrigerator connected parallel to the main refrigerator and having a refrigerant-filled chamber, switch control means for controlling the switching operation between the supply of a refrigerant used in the main refrigerator to the sub-refrigerator, and the stop of the supply of the refrigerant, on the basis of predetermined conditions.

Abstract: A high-power thermoacoustic refrigerator including a half-wave length resonator, first and second drivers located in housings at first and second ends of said resonator, two pusher cones, a plurality of heat exchangers, a first and second stack, utilizing a compressible gas mixture capable of being tuned to the driver resonance frequency, a half-wave length tube, fluids disposed within said heat exchangers for transferring heat, and voice coils wired 180 degrees out of phase for compressing said compressible fluid into a standing wave oscillating within said resonator.

Abstract: A displacer assembly for use with a thermal regenerative machine has a housing configured to receive a displacer therein. The displacer has a drive area formed by a rod portion of the displacer that extends through a hole in the housing to form a clearance seal therebetween. The housing and displacer form a sub-assembly that can be pre-assembled to provide a clearance seal prior to assembly with a linear drive motor. Another feature is provided by a fluid flow path extending centrally of the displacer rod, and in part along an outer peripheral surface of the rod adjacent a heat rejection region of the housing. Heat transference there along provides for a more efficient stirling thermodynamic cycle in response thereto.

Abstract: A cooling system utilizes a pulse-tube expander having a hollow pulse tube and three hollow regenerator tubes that lie parallel to and laterally displaced from the pulse tube, and are arranged in triangular fashion about the pulse tube. A cold end of each of the regenerator tubes is in gas pressure communication with a cold end of the pulse tube. Pulsing gas pressure is supplied to a warm end of each of the regenerator tubes, and a surge volume communicates with a warm end of the pulse tube. A heat sink is provided at the warm end of the regenerator tubes and the pulse tube to remove heat therefrom and from the pulsing gas. Heat is extracted from a heat load at the cold end of the regenerator tubes and the pulse tube.

Abstract: A refrigerator having a heat pump mounted within the insulated portion of the refrigerator cabinet which is cooled by the heat pump. The heat pump is a Stirling cycle or Rankine cycle heat pump, is used to cool the interior of the refrigerator cabinet, and is mounted in an insulated housing to limit the transfer of heat from the heat pump into the refrigerator cabinet. A heat transporting conduit connects the heat pump to an exterior heat exchanger mounted outside the refrigerator cabinet.

Abstract: A multi-staged gas cycle refrigerator having a first stage regeneration part including a compression piston, a second stage regeneration part including a double inlet pulse tube and a buffer is described. Temperatures below 10K are achieved without leakage of refrigerant gas, this configuration resulting in the improvement of efficiency and reduction of cost.

Abstract: Superconducting magnet and regenerative refrigerator can be reduced in size of the apparatus and is capable of reducing the evaporating amount of liquid helium. A coil portion second thermal shield 17a and a coil portion thermal shield 8a are disposed so as to enclose a coil portion helium tank 2a which contains superconducting coil 1. Further, a helium portion second thermal shield 17b and a helium reservoir portion thermal shield 8b are disposed so as to enclose a helium reservoir tank 2b which stores liquid helium 3. A coil portion second thermal shield 17a and a coil portion thermal shield 8a are cooled by a coil portion 2-stage type Gifford-McMahon cycle refrigerator 50a while a helium portion second thermal shield 17b and a helium reservoir portion thermal shield 8b are cooled by a helium reservoir portion 2-stage type Gifford-McMahon cycle refrigerator 50b.

Abstract: This invention relates to a Stirling engine as a refrigerating machine or heat pump having improved heat transfer to the working gas or improved heat transfer from the working gas of the Stirling engine to a cooling medium with simultaneous reduction of the dead space in the engine. The Stirling engine operates with injection or atomisation of a heat transfer fluid into the working spaces of the engine, due to which the heat transfer between the heat transfer medium and the working gas is improved.

Abstract: An improved heat exchanger for use in a gas compression/expansion apparatus. The heat exchanger comprises: a tube connected with a compression/expansion space of a compression/expansion cylinder of the apparatus; a central cylinder coaxially disposed in the tube such that a narrow gap for the working gas is formed only between the central cylinder and the tube. The heat exchanger may liberate heat from, or providing heat to, the compression/expansion cylinder through heat transfer between the working gas in the tube and an ambient medium surrounding said tube. The heat exchanger is capable to serve as a low/high temperature heat source for an external heat load.

Abstract: A free-piston Vuilleumier heat pump in which displacers having a spring-operated resonance system, controls the heating energy and cooling energy outputs by controlling strokes of a hot displacer and a cold displacer. The control of the displacer strokes is performed by controlling the working gas temperature in a hot working space. Furthermore, the control of the displacer strokes may be performed by controlling a motor output while keeping the operation frequency of the motor mounted for at least one of the hot displacer and the cold displacer, in the vicinity of a resonance frequency which is determined by the driving system of the hot displacer and the cold displacer.

Abstract: A pulse tube cooler comprising pulse tube, a regenerator concentrically disposed around the pulse tube, and a thermal insulator concentrically disposed between the pulse tube and the regenerator. More specifically, the concentric pulse tube cooler comprises a cold finger assembly disposed at a first end of the concentric pulse tube cooler, a heat exchanger assembly disposed at a second end of the concentric pulse tube cooler that is coupled to a a surge volume and that is coupled to a source of operating gas, and a pulse tube expander assembly slidably and sealably secured to the heat exchanger assembly. The pulse tube expander assembly comprises a central pulse tube, a thermal insulator concentrically disposed around the central pulse tube, and a regenerator concentrically disposed around the concentric insulation tube. The pulse tube expander assembly comprises a slidable axial seal for slidably and sealably securing the pulse tube expander assembly to the heat exchanger assembly.

Abstract: A cooling system includes a cold-accumulating refrigerator, and a cooling circuit. The cold-accumulating refrigerator includes a cold accumulator. The cooling circuit includes a heat exchanger. The heat exchanger is thermally brought into contact with a portion of the cold accumulator whose temperature is varied from a high temperature to a low temperature by a working medium flowing therein. Thus, it is possible to utilize cold produced by the working medium flowing in the cold accumulator in one cycle (e.g., from a high temperature to a low temperature, and from a low temperature to a high temperature), thereby remarkably enhancing the cooling system in terms of cooling efficiency.

Abstract: A split Stirling cycle type of cryogenic cooler (10) includes a compressor portion (12) and an expander portion (14). The expander portion (14) is of the "cold finger" type, and is configured to operate in near-resonance with the characteristic cyclic operating rate of the compressor portion (12). As a result, an improved performance of the cooler results both during cool down from ambient temperatures and after cool down. Additionally, a quiet operation of the cooler is provided both during and after cool down to cryogenic temperatures.

Abstract: The regenerating material according to the present invention comprises two alloy phases which differ in a content of rare earth elements. Of these alloy phases, a dominant phase in the regenerating material is defined as a main phase, and the other phase is defined as a sub-phase. A plurality of particles, each of which consists of a granular main phase and a sub-phase present on the surface of the main phase, gathers to form an aggregate. Otherwise, a sub-phase present in a main phase in the form of fiber. The refrigerator according to the present invention comprises a regenerator charged with above-mentioned regenerating material, a coolant gas and an expansion means for expanding the coolant gas.

Abstract: The invention relates to a Stirling cooler, comprising a compressor for generating a time-varying pressure in a gaseous medium, a cooling element provided with at least a displacer and at least a regenerator and additionally comprising a connecting line between the compressor and the cooling element. The incorporation of heat flow-reduction means for reducing the heat flow from the compressor to the cooling element causes a sharp drop in temperature on the warm side of the cooling element as a result of which heat sinking will no longer be required.

Abstract: A refrigerator with a regenerator is provided which is supported by a holder. The refrigerator has a cylinder having an inner circumferential surface matching a circular tube shape, a displacer being disposed in the cylinder and forming an expansion space near at one end of the inside of the cylinder, a groove pattern having a groove formed along the direction intersecting the axial direction of the displacer, the groove allowing a gas flowing through a gap between the cylinder and displacer from one end to the other end of the outer circumferential surface of the displacer to positively heat-exchange with the cylinder and displacer, and a main gas passage for supplying gas to the expansion space of the cylinder and recovering the gas from the expansion space.

Abstract: Superconducting magnet and regenerative refrigerator can be reduced in size of the apparatus and is capable reducing the evaporating amount of liquid helium. A coil portion second thermal shield 17a and a coil portion thermal shield 8a are disposed so as to enclose a coil portion helium tank 2a which contains superconducting coil 1. Further, a helium portion second thermal shield 17b and a helium reservoir portion thermal shield 8b are disposed so as to enclose a helium reservoir tank 2b which stores liquid helium 3. A coil portion second thermal shield 17a and a coil portion thermal shield 8a are cooled by a coil portion 2-stage type Gifford-McMahon cycle refrigerator 50a while a helium portion second thermal shield 17b and a helium reservoir portion thermal shield 8b are cooled by a helium reservoir portion 2-stage type Gifford-McMahon cycle refrigerator 50b.

Abstract: An electromechanical cryocooler is disclosed for substantially reducing vibrations caused by the cooler. The direction of the force of the vibrations is measured and a counterforce sufficient to substantially reduce this vibration is calculated and generated. The counterforce is 180.degree. out of phase with the direction of the force of the vibrations.

Abstract: An acoustic resonator includes a chamber which contains a fluid. The chamber has a geometry which produces self-destructive interference of at least one harmonic in the fluid to avoid shock wave formation at finite acoustic pressure amplitudes. The chamber can have reflective terminations at each end or a reflective termination at only one end. A driver mechanically oscillates the chamber at a frequency of a selected resonant mode of the chamber. The driver may be a moving piston coupled to an open end of the chamber, an electromagnetic shaker or an electromagnetic driver.

Abstract: A cooling system includes a cold-accumulating refrigerator, and a cooling circuit. The cold-accumulating refrigerator includes a regenerator. The cooling circuit includes a main circuit, and a branched circuit. The main circuit includes a counterflow heat exchanger. The branched circuit is branched from an upstream portion of the main circuit, and joined to a downstream portion thereof, thereby reducing one of the flows of a refrigerant, flowing in a high-pressure-side passage and a low-pressure-side passage which are disposed in the counterflow heat exchanger, with respect to the other one of the flows. Moreover, the branched circuit includes a heat exchanger, and the heat exchanger is thermally brought into contact with a portion of the regenerator whose temperature is varied from a high temperature to a low temperature by another refrigerant flowing therein.

Abstract: A hybrid thermoelectric/Joule-Thomson cryostat with a finite cryogenic gas supply is configured to greatly increase the cold operating time of a infrared detector array. A Joule-Thomson cryostat is located within a dewar vessel along with the infrared detector array to be cooled. Cryogenic gas from a cryogenic gas source is pre-cooled by a thermoelectric cooler at a location remote from the dewar vessel. Final cooling of the cryogenic gas is then performed by a demand flow Joule-Thomson cooler which has the ability to provide the low temperatures necessary for operation of an infrared detector. The operating period of the cryogenic gas supply and Joule-Thomson cryostat are increased by the cryogenic assistance of the thermoelectric cooler.

Abstract: An improved cryogenic cooler 100 includes a flange 106 with an elongated pressure vessel 120 extending therefrom. The pressure vessel 120 is connected to the flange 106 at a proximal end thereof. The pressure vessel 120 is adapted to cool a surface in the proximity of the distal end thereof. Vibration isolation is provided at both proximal and distal ends of the elongated pressure vessel. A coupler 126 serves to maintain a gap between the distal end of the pressure vessel 120 and the surface at cryogenic temperatures. In a specific embodiment, the coupler 234 has a coefficient of thermal expansion which is less than the coefficient of thermal expansion of an end cap 224 on the pressure vessel. The coefficients of expansion are chosen to provide a tight slip fit between the cooler and the coupler at ambient temperatures and a very small continuous air gap at cryogenic temperatures. Another novel feature is the provision of an energy-absorbing ring 114 within the flange to dissipate vibration therein.

Abstract: A two stage Gifford-McMahon cryocooler having a low temperature stage for reaching approximately 10K, wherein the low temperature stage includes a passive magnetic heat regenerator selected from the group consisting of Er.sub.6 Ni.sub.2 Sn, Er.sub.6 Ni.sub.2 Pb, Er.sub.6 Ni.sub.2 (Sn.sub.0.75 Ga.sub.0.25), and Er.sub.9 Ni.sub.3 Sn comprising a mixture of Er.sub.3 Ni and Er.sub.6 Ni.sub.2 Sn in the microstructure.

Abstract: A temperature control apparatus and method for active control of a Stirling-cycle cryocooler cold finger tip temperature, by adjusting the cryocooler compressor piston stroke amplitude. In a control loop of the Stirling cryocooler, having a compressor in which the pistons are reciprocated by linear motors at fundamental frequency and the length of a stroke of the piston is varied as a direct function of cryocooler temperature, temperature is sensed at the cryocooler cold finger tip and the temperature signal is compared with a set temperature signal to produce a temperature error signal. This signal is input in a PID control law module which uses proportional, derivative, and integrated temperature error information to generate the required compressor piston stroke amplitude change for achieving the precision temperature control.

Abstract: A detecting device having: a compressor driven by an electric signal for supplying and recovering He gas at an operation cycle of 10 Hz to 400 Hz; a He gas refrigerator for transferring the He gas to and from the compressor and expanding the tie gas to generate cold; driving power supply means for intermittently supplying a driving power to the compressor at a certain interval; and a detector to be cooled by the He gas refrigerator.