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Active Coolers for cooling Infrared Detector on satellite payloads. Presentation By Milind B Naik TIFR, MUMBAI. Stirling Cooler. Types of coolers. Passive Coolers Radiators Stored Cryogens Active Coolers Stirling cycle (this presentation covers this cooler ) Pulse tube
Active Coolers for cooling Infrared Detector on satellite payloads Presentation By Milind B Naik TIFR, MUMBAI Stirling Cooler
Types of coolers • Passive Coolers • Radiators • Stored Cryogens • Active Coolers • Stirling cycle (this presentation covers this cooler ) • Pulse tube • Joule-Thompson • Brayton • Adiabatic Demagnetization • 3He 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 70K ) • 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 60-80K to 15-30K.
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.
Typical cryocooler to be used for satellite payload MOTOR COLD FINGER RICOR ( ISRAEL)
Working of stirling cryocooler Hot side (with heat sink) Cold side (cold finger) Hot side Cold side (cold finger)
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-dewarCrcycooler assembly • Crycooler Fill and purge with Helium • Various leak tests • Functional tests • Calibrations • Others.