Abstract: The disclosed invention provides a bridge voltage inversion circuit for vacuum gauge and a pressure gauge sensor that includes the bridge voltage inversion circuit. The bridge voltage inversion circuit for a pressure gauge includes a reference capacitance, a sensor capacitance, and a transformer including a primary winding and a secondary winding that outputs a bridge voltage. The reference capacitor is connected to a first side of the secondary winding of the transformer, and the sensor capacitor is connected to a second side of the secondary winding of the transformer. The sensor capacitor senses and responds to a pressure, and a capacitance of the sensor capacitor is at a minimum when the pressure is at vacuum. The capacitance of the sensor capacitor at vacuum is less than a capacitance of the reference capacitor.

Abstract: A capacitive diaphragm gauge (CDG) is positioned in a pressure sensing section of a pressure measuring unit. The CDG is heated to maintain the CDG at a temperature selected to reduce contamination build-up on the diaphragm of the CDG. The pressure sensing section is connected to a first mounting interface of a thermal barrier. A second mounting interface of the thermal barrier is connected to an electronics section. The thermal barrier includes a plurality of struts that mechanically interconnect the two mounting interfaces. The struts have sizes selected to be sufficiently large to cantilever the electronics section from the sensing section. The sizes of the struts are selected to be sufficiently small to reduce the heat transfer from the first mounting interface to the second mounting interface to maintain the second mounting interface below a selected maximum temperature. The struts reduce heat transfer without reducing structural integrity.

Abstract: A recovery cryostat, external to a cryogen storage tank, uses a cryocooler to condense vapor of cryogen from the storage tank and return the cryogen to the storage tank as a liquid. The process may be continuous or cyclical depending on the orientation of the recovery cryostat. If the recovery cryostat is located such that liquid can drain back to the storage tank, the process can be continuous. If the liquid cannot be drained back, a valve on the liquid return line is closed while the cryocooler condenses the vapor, a valve on the vapor supply line is then closed, the valve on the liquid return line is opened, and pressure in the recovery cryostat is increased to drive the liquid out. The storage tank is a type that can have vapor that boils off external to the tank be returned to the vapor space above the liquid in the tank.

Abstract: A universal controller for integration of cryogenic equipment, requiring different control mechanisms, onto a single operating platform. The universal controller may include a power supply element that is configured to simultaneously drive a plurality of cryogenic devices that have different power supply requirements and a protocol translator element that is configured to enable communication between a plurality of cryogenic devices that use different, incompatible communication protocols, wherein the protocol translator element translates communications sent by a first type of cryogenic device from a first cryogenic device communication protocol into a second cryogenic device communication protocol and translates communications sent by a second type of cryogenic device from a second cryogenic device communication protocol into the first cryogenic device communication protocol, enabling the first type of cryogenic device and the second type of cryogenic device to communicate with each other.

Abstract: 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.

Abstract: A heat station for a GM or Stirling cycle expander provides a versatile, efficient, and cost effective means of transferring heat from a remote load at cryogenic temperatures that is cooled by a circulating cryogen to the gas in a GM or Stirling cycle expander as the gas flows between a regenerator and a displaced volume. The heat exchanger includes a shell that has external and internal fins that are thermally connected, are aligned parallel to the axis of the shell, and are enclosed in a housing having a single port on the bottom of the housing.

Abstract: 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.

Abstract: A Gifford-McMahon (GM) type double-inlet pulse tube system providing cooling at cryogenic temperatures is provided. The system has a co-axial double-inlet valve that includes a base having an adjustable port, a fixed needle partially engaged in one end of the adjustable port, an adjustable needle partially engaged in another end of said adjustable port, and a body for housing the base, the fixed needle and the adjustable needle. The base is configured to be adjustable along an axial direction. The adjustable needle is arranged co-axially with the fixed needle. The adjustable port and the adjustable needle are configured to control an alternating current (AC) flow and a direct current (DC) flow between the stem port and the end port and to produce the DC flow in either direction between the stem port and the end port.

Abstract: A superconducting magnet device includes a superconducting coil; a radiation shield that thermally protects the superconducting coil; a main cold head that cools the superconducting coil; a sub-cold head that cools the radiation shield; a common compressor that supplies a refrigerant gas to the main cold head and the sub-cold head; a first temperature sensor that measures a temperature of the radiation shield; a second temperature sensor that measures a temperature of the superconducting coil; and a controller configured to activate the sub-cold head for initial cooling of the superconducting magnet device, stop the sub-cold head based on an output of the first temperature sensor or the second temperature sensor, and operate the main cold head in a state where the sub-cold head is stopped.

Abstract: 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.

Abstract: 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.

Abstract: A Gifford-McMahon (GM) type double-inlet pulse tube system providing cooling at cryogenic temperatures is provided. The system has a co-axial double-inlet valve that includes a base having an adjustable port, a fixed needle partially engaged in one end of the adjustable port, an adjustable needle partially engaged in another end of said adjustable port, and a body for housing the base, the fixed needle and the adjustable needle. The base is configured to be adjustable along an axial direction. The adjustable needle is arranged co-axially with the fixed needle. The adjustable port and the adjustable needle are configured to control an alternating current (AC) flow and a direct current (DC) flow between the stem port and the end port and to produce the DC flow in either direction between the stem port and the end port.

Abstract: 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.

Abstract: This invention relates to oil lubricated helium compressor units for use in cryogenic refrigeration systems, operating on the Gifford McMahon (GM) or Brayton cycle. The objective of this invention is to provide redundancy by having a water cooled compressor manifolded to an air cooled compressor and sensors to detect faults so that an expander can be kept running if there is a failure in either the water or air supply.

Abstract: A hybrid expander for producing refrigeration at a cryogenic temperature includes a Brayton expander producing refrigeration at a first temperature; a GM expander producing refrigeration at a second temperature, the first temperature being colder than the second temperature, the second temperature being 200K or less. A high pressure line receives a gas from a compressor at a first pressure and supplies it at the first pressure to the Brayton expander and the GM expander simultaneously. A low pressure line returns the gas to the compressor at a second pressure from the Brayton expander and the GM expander, the first pressure being greater than the second pressure. The Brayton expander piston is attached to the cold end of the GM expander displacer and the Brayton expander piston and the GM expander displacer reciprocating together.

Abstract: This invention relates to oil lubricated helium compressor units for use in cryogenic refrigeration systems, operating on the Gifford McMahon (GM) or Brayton cycle. The objective of this invention is to provide redundancy by having a water cooled compressor manifolded to an air cooled compressor and sensors to detect faults so that an expander can be kept running if there is a failure in either the water or air supply.

Abstract: An expansion engine operating on a Brayton cycle which is part of a system for producing refrigeration at cryogenic temperatures that includes a compressor, a counter-flow heat exchanger, and a load that may be remote, which is cooled by gas circulating from the engine. The engine has a piston in a cylinder which has nearly the same pressure above and below the piston while it is moving. A valve connecting the warm end of the cylinder to a buffer tank allows a partial expansion and recompression of gas in the cold displaced volume that increases the refrigeration produced in each cycle with the same compressor flow rate.

Abstract: Losses in the connecting line between the Pressure Wave Generator and the cold head of a GM type pulse tube refrigerator, are reduced while maintaining or improving upon the desirable features of a standard corrugated hose connecting line including vibration isolation, separation distance, and mounting convenience. The basic means are to reduce the internal void volume of the convolutions in a corrugated hose in combination with reducing the number of corrugations, adding fillers to the void volumes, and vibration absorbing coatings.

Abstract: A universal controller for integration of cryogenic equipment, requiring different control mechanisms, onto a single operating platform. The universal controller may include a power supply element that is configured to simultaneously drive a plurality of cryogenic devices that have different power supply requirements and a protocol translator element that is configured to enable communication between a plurality of cryogenic devices that use different, incompatible communication protocols, wherein the protocol translator element translates communications sent by a first type of cryogenic device from a first cryogenic device communication protocol into a second cryogenic device communication protocol and translates communications sent by a second type of cryogenic device from a second cryogenic device communication protocol into the first cryogenic device communication protocol, enabling the first type of cryogenic device and the second type of cryogenic device to communicate with each other.

Abstract: This invention relates generally to oil lubricated helium compressor units for use in cryogenic refrigeration systems, operating on the Gifford McMahon (GM) cycle. This invention provides redundancy between water cooling and air cooling if there is a blockage in the water or air supply by having air and water cooled after-coolers in series or parallel.