A cryocooler includes: a magnetic shield axially extending along a second-stage cylinder from a second-stage cooling stage outside the second-stage cylinder and disposed separated from a first-stage cooling stage by an axial separation distance, wherein an annular space open to a helium atmosphere is formed between the second-stage cylinder and the magnetic shield, and the axial depth of the annular space is longer than the axial separation distance; and a convection suppression member, for suppressing axial convection of helium gas in the annular space caused by temperature difference between the second-stage cylinder and the magnetic shield, is disposed in the annular space and is of longer axial length than the axial separation distance.

Techniques are disclosed for systems and methods to control operation of a cryocooler/refrigeration system to provide cryogenic and/or general cooling of a device or sensor system. A cryocooler controller includes a motor driver controller configured to generate motor driver control signals based on operational parameters corresponding to operation of a cryocooler controlled by the controller, and a motor driver configured to generate corresponding drive signals to drive a motor of the cryocooler. The motor driver includes a first stage with a first pair of switches coupled serially between an input of the motor driver and a ground of the motor driver, a second pair of switches coupled serially between an output of the first stage and the ground of the motor driver, and an inductor coupled between the first and second pairs of switches, where operation of each switch is independently controlled by the motor driver control signals.

A cryostat arrangement includes a superconducting magnet to be cooled by an active cryocooler. The cryocooler includes a coolant circuit with a compressor, a cold head, and a cold finger in thermal contact with the magnet. A volumetric vessel containing cryogenic fluid is thermally coupled to the magnet. The volumetric vessel is connected to the coolant circuit by a pressure-resistant line. A fluidic component influences the flow rate through the line in a defined manner such that the cryogenic fluid flows between the volumetric vessel and the coolant circuit with a time constant of at least 15 minutes. The cryostat can be operated in a cryogen-free manner and permits a sufficiently long time to quench in the event of operational malfunctions.

A cryocooler includes a second-stage cooling stage, a second cylinder which includes the second-stage cooling stage on a terminal of the second-stage cylinder, a second-stage displacer which includes a magnetic regenerator material and is accommodated in the second-stage cylinder so as to be able to reciprocate in the second-stage cylinder, and a tubular magnetic shield which is installed on the second-stage cooling stage and extends along the second-stage cylinder outside the second-stage cylinder. The magnetic shield is formed of a normal conductor and a product of an electrical conductivity in a temperature range of 10 K (Kelvin) or less and a thickness of the tubular magnetic shield is 60 MS (Mega-Siemens) to 1980 MS.

A cool air supplying apparatus includes a swash plate shaft connected to a motor and extending in a predetermined axial direction; a compression swash plate obliquely coupled to the swash plate shaft; a compression piston configured to reciprocate in the axial direction by the rotation of the compression swash plate; a compression cylinder in which a working fluid is compressed by the compression piston, an expansion swash plate obliquely coupled to the swash plate shaft; an expansion piston configured to reciprocate in the axial direction by the rotation of the expansion swash plate; and an expansion cylinder arranged with the compression cylinder in the axial direction and configured to expand a working fluid compressed by the compression cylinder; and the compression swash plate and the expansion swash plate are installed in the swash plate shaft with a predetermined phase difference.

Techniques are disclosed for systems and methods to reduce mechanical vibrations within a cryocooler/refrigeration system configured to provide cryogenic and/or general cooling of a device or sensor system. A cryocooler includes a motor driver controller configured to receive operational parameters and generate motor driver control signals and/or balancer system control signals based, at least in part, on the received operational parameters, and a motor driver configured to receive the control signals and generate drive signals to drive a motor and/or a balancer system of the cryocooler. The cryocooler includes a motorized and/or actively balanced expander configured to drive and/or balance motion of a displacer of the expander. The expander includes a magnet ring fixed to the displacer and a motor coil disposed within a cylinder head of the motorized and/or actively balanced expander.

A mechanical system, such as cryogenic refrigerator system, is described. The system comprises two or more axial moving elements generating two or more cyclic forces along parallel axes and a vibration attenuation unit. The cyclic forces are provided with common frequency and certain phase difference between them. The vibration attenuation unit is configured for attenuating vibrations corresponding to two or more modes of vibrations characterized by a frequency corresponding to operation frequency of said two or more cyclic forces.

A cooling system includes a first dewar configured to house a first optical imaging device, a second dewar configured to house a second optical imaging device, and a Stirling cycle refrigerator. The Stirling cycle refrigerator can include a compressor, a first expander in fluid communication with the compressor and in thermal communication with the first dewar, and a second expander in fluid communication with the compressor and in thermal communication with the second dewar.

Apparatus for controlling a cryogenic cooling system is described. A supply gas line (3A) and a return gas line (3B) are provided which are coupled to a compressor (1) and to a mechanical refrigerator (2) via a coupling element (4). The coupling element is in gaseous communication with the supply (2A) and return gas lines and supplies gas to the mechanical refrigerator (2). The pressure of the supplied gas is modulated by the coupling element in a cyclical manner. A pressure sensing apparatus (6) monitors the pressure in at least one of the supply and return gas lines. A control system (5) is used to modulate the frequency of the cyclical gas pressure supplied by the coupling element in accordance with the pressure monitored by the pressure sensing apparatus. An associated method of controlling such a system is also described.

Cryocooler health monitoring systems and methods are provided. In one example, a method includes determining, for each setpoint temperature of a plurality of setpoint temperatures, a respective power applied to a cryocooler to set a cold tip of the cryocooler to the setpoint temperature. The method further includes determining a first load line associated with the cold tip based on the plurality of setpoint temperatures and the respective powers applied to the cryocooler. The method further includes determining a health metric associated with the cold tip based on the first load line and a reference load line associated with the cryocooler. Related devices and systems are also provided.