Joule-Thomson miniature coolers for optronics

Cryogenic technology tailored to very rapid cool-down operations

This range of coolers is used for the cryogenic refrigeration by Joule-Thomson cycle, in a temperature range of 80-100° K. It is used in infrared detectors or electronic components, on the ground or on-board, in conditions of harsh environmental stress such as defense systems.
For this type of application, the technological simplicity and sturdiness of miniature coolers based on a compressed gas unit are evidence of reliability and ease of integration.

 

Benefits

  • Very fast cool-down time (as low as 1s)
  • Good temperature stability
  • Significant autonomy after launch
  • Long operating lifetime
  • Greater accuracy of cooled components

 

How does it work?

The range comprises coolers that differ according to refrigerant capacity, cool-down time and autonomy specific to the application. These levels of performance are obtained as a function of the type of gas used, pure gas like nitrogen or argon, or gas mixture, and the inlet pressure of this gas. 

These coolers comprise: 

  • A heat exchanger in which the high pressure gas is pre-cooled in counterflow by the expanded low pressure cold gas 
  • An expansion outlet of fixed cross-section (single flow devices), or dual cross-section (dual flow devices), or variable cross-section (metered devices) 
  • A valve with actuator and obturator to vary the cross-section of the expansion outlet (dual flow and metered devices) 
  • Differential contraction valve for rapid cool-down of a significant thermal mass 

JT coolers are mounted in cryostats with thermal insulation vacuum. The gas is liquefied at the well bottom on which the infrared detector for cooling is assembled.

 

Range

 

Single flow JT

Dual flow JT

Self regulated JT 

Cool-down time at 20°C

< 2 s

< 10 s

< 60 s

Cryognic temperature

100 K

95 K

80 K

Gaz

Argon

Argon or mixtures

Nitrogen

Typical autonomies

> 10 s

> 1 mn

> 1 h

Main Applications 

Infrared detector in missiles

Infrared detector in missiles

Infrared detector in missiles, radar, thermal cameras

Specific products on demand.

 

Main technical characteristics

  • Cooling operations based on different types of gas: argon, nitrogen, freon, air, nitrogen argon mixtures,
  • Dewar diameter: 3.3 mm, 5.18 mm, 7.23 mm (or on request)
  • Thermal mass to be cooled: from 15 J to 300 J (or on request)
  • Heat loss: from 130 mW to 200 mW (or on request)
  • Very low induced vibration level

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Standards

  • Gas purity: DEF STAN 58-96 issue 2
  • Environment: MIL STD 810D

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