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Active Coolers for cooling Infrared Detector on satellite payloads Stirling Cooler Presentation By Milind B Naik TIFR, MUMBAI
Types of coolers • Passive Coolers • Radiators • Stored Cryogens • Active Coolers • • Stirling cycle (this presentation covers this cooler ) Pulse tube Joule-Thompson Brayton Adiabatic Demagnetization 3 He coolers Optical cooling Peltier effect coolers
• Passive Coolers • Radiators – Radiators are panels radiating heat according to Stefan's Law – extremely high reliability – low mass and a lifetime limited only by surface contamination and degradation – limitations on the heat load and temperature (typically in the milliwatt range at 70 K ) – Multiple stages are often used • Stored cryogens. – Dewars containing a cryogen such as liquid helium or solid neon – excellent temperature stability with no exported vibrations – substantially increases the launch mass of the vehicle – limit the lifetime of the mission to the amount of cryogen stored
• Active Coolers • Stirling cycle. – These coolers are based on causing a working gas to undergo a Stirling cycle which consists of 2 constant volume processes and two isothermal processes. – Devices consist of a compressor pump and a displacer unit with a regenerative heat exchanger, known as a `regenerator'. – Stirling cycle coolers were the first active cooler to be used successfully in space and have proved to be reliable and efficient. – Recent years have seen the development of two-stage devices which extend the lower temperature range from 60 -80 K to 1530 K.
Advantages/disadvantages of different types of cooler technology
Some examples of missions using active coolers • Missions are listed as vehicle/instrument. • Design lifetime has been quoted if the instrument is yet to be launched or failed due to another component. • Excluding electronics. • STS/BETSE was a technology demonstrator. • UARS/ISAMS figures per cooler running at 83% stroke.
example of missions using active coolers
Typical cryocooler to be used for satellite payload MOTOR COLD FINGER RICOR ( ISRAEL)
Set of cold-finger available for Cryocooler
Working of stirling cryocooler Hot side (with heat sink) Cold side (cold finger) Hot side Cold side (cold finger)
Working of stirling cryocooler
Test-dewar for cryocooler testing Cryocooler Test-dewar
Test-dewar for cryocooler testing Temperature Sensor Vacuum
• Various processes involved for testing Stirling cryocooler – Design, development of test-dewar with vacuum seal, feedthrough wires, optical window, temperature sensor integration with cold-finger etc. – Assembly , evacuation of test-dewar. Crcycooler assembly – Crycooler Fill and purge with Helium – Various leak tests – Functional tests – Calibrations – Others.