Abstract: A non-contact angular motion measuring device includes a mirror configured to move or rotate about a pivot axis. The device also includes a curved target, circularly symmetric around an axis normal to the mirror. The device further includes at least one pair of sensors configured to emit fields towards the curved target rather than the mirror.

Abstract: An inertance tube and a surge volume for a pulse tube refrigerator system may be integrally coupled together, such as by the inertance tube being at least in part a channel in a wall of the surge volume. The surge volume may have a helical channel in an outer wall that forms part of the inertance tube. The surge volume tank may be surrounded by a cover that closes off the channel to form the inertance tube as an integral part of the surge volume. The inertance tube may have a non-circular cross section shape, such as a square shape or non-square rectangular shape. The channel may be tapered, perhaps changing aspect ratio. Alternatively, the inertance tube may be a separate tube having a non-circular shape, which may be wrapped around at least part of the surge volume.

Abstract: Disclosed are a low vibration cryocooler and a method of reducing vibration in a cryocooler. The cryocooler can be a Stirling class cryocooler includes at least one motor that drives a mass, the motor having a main drive winding and a separate trim winding. A motor controller outputs a main drive signal that is coupled to the main drive winding and a separate vibration reducing signal that is coupled to the trim winding.

Abstract: An inertance tube and a surge volume for a pulse tube refrigerator system may be integrally coupled together, such as by the inertance tube being at least in part a channel in a wall of the surge volume. The surge volume may have a helical channel in an outer wall that forms part of the inertance tube. The surge volume tank may be surrounded by a cover that closes off the channel to form the inertance tube as an integral part of the surge volume. The inertance tube may have a non-circular cross section shape, such as a square shape or non-square rectangular shape. The channel may be tapered, perhaps changing aspect ratio. Alternatively, the inertance tube may be a separate tube having a non-circular shape, which may be wrapped around at least part of the surge volume.

Abstract: A regenerative refrigeration system includes one or more control devices that utilize micro electro mechanical systems (MEMS) technology. Such MEMS devices may be small in size, on a scale such that it can be introduced into a refrigeration system, such as a cryocooler, without appreciably affecting the size or mass of the refrigeration system. Through the use of MEMS devices, dynamic control of the system may be achieved without need for disassembly of the system or making the system bulky. Suitable regenerative refrigeration systems for use with the MEMS devices include pulse tube coolers, Stirling coolers, and Gifford-McMahon coolers.

Abstract: A two-stage hybrid cryocooler includes a first-stage Stirling expander having a first-stage regenerator having a first-stage-regenerator inlet and a first-stage-regenerator outlet, and a second-stage pulse tube expander. The second-stage pulse tube expander includes 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, and a pulse tube having a pulse-tube inlet in gaseous communication with the second-stage regenerator outlet, and a pulse-tube outlet. 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 has 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 is in gaseous communication with the pulse-tube pressure-drop outlet.

Abstract: A cryogenic refrigeration system includes an expansion nozzle having a high-pressure nozzle inlet and a low-pressure nozzle outlet, and a compressor having a compression device, such as a pair of opposing pistons, operable to compress gas within a compression volume. The compression volume has an inlet port and an outlet port. A flapper inlet valve has an inlet valve inlet, and an inlet valve outlet in gaseous communication with the inlet port of the compression volume. The inlet valve opens when a gaseous pressure at the inlet valve inlet is sufficiently greater than a gaseous pressure in the compression volume to overcome a spring force of the flapper inlet valve. A flapper outlet valve has an outlet valve inlet in gaseous communication with the outlet port of the compression volume, and an outlet valve outlet in gaseous communication with the nozzle inlet.

Abstract: A two-stage cryocooler (10) includes an ambient temperature portion (12), a first-stage temperature portion (14), and a second-stage temperature portion (16). The ambient temperature portion includes a surge volume (44) that is coupled to and in communication with the first-stage temperature portion. The surge volume may be coupled to a first-stage interface (36) of the first-stage temperature portion by use of an inertance tube (42). Locating the surge volume in the ambient temperature portion may advantageously reduce size and mass of the first-stage temperature portion. Also, thermal losses may be reduced by maintaining the surge volume at ambient temperature. Space and structural requirements for maintaining the system may be met more easily with the surge volume maintained in the ambient temperature portion of the two-stage cooler. The surge volume may be a separate unit, or may be a plenum or other chamber within an expander in the ambient temperature portion.

Abstract: A cryogenic refrigeration system includes an expansion nozzle having a high-pressure nozzle inlet and a low-pressure nozzle outlet, and a compressor having a compression device, such as a pair of opposing pistons, operable to compress gas within a compression volume. The compression volume has an inlet port and an outlet port. A flapper inlet valve has an inlet valve inlet, and an inlet valve outlet in gaseous communication with the inlet port of the compression volume. The inlet valve opens when a gaseous pressure at the inlet valve inlet is sufficiently greater than a gaseous pressure in the compression volume to overcome a spring force of the flapper inlet valve. A flapper outlet valve has an outlet valve inlet in gaseous communication with the outlet port of the compression volume, and an outlet valve outlet in gaseous communication with the nozzle inlet.

Abstract: A pulse tube expander includes a regenerator, a pulse tube, a porous plug phase shifter, and a surge tank, in series gaseous communication with each other. The porous plug phase shifter is made of a porous material such as a sintered mass or a packed solid bed of distinct, free-flowing bodies. The porous plug phase shifter introduces a phase shift between the pressure wave and the mass flow rate in the pulse tube expander. The porous plug phase shifter is resistant to clogging due to contamination that may be present in the system.

Abstract: A hybrid two-stage cryocooler includes a first-stage Stirling expander having a first-stage interface and a Stirling expander outlet, a thermal-energy storage device in thermal communication with first-stage interface, and a second-stage pulse tube expander with a pulse tube inlet. A gas flow path extends between the Stirling expander outlet and the pulse tube inlet, and a heat exchanger is in thermal contact with the gas flow path. The relative cooling power of the first and second stages may be controlled to increase the cooling power of the second stage relative to the first stage in response to an increased heat load to the second stage. The thermal-energy storage device acts as a thermal buffer during this period, and is later cooled when the relative cooling power is adjusted to increase the cooling power of the first stage.

Abstract: A hybrid two stage expander having a first stage Stirling expander coupled to a second stage pulse tube expander. Both stages are pneumatically driven by a common reciprocating compressor in a typical application. The first stage Stirling expander provides high thermodynamic efficiency which removes a majority of the heat load from gas within the cryocooler. The second stage pulse tube expander provides additional refrigeration capacity and improved power efficiency with little additional manufacturing complexity since it has no moving parts.

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 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 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.