active coolers for cooling infrared detector on satellite payloads presentation by milind b naik...
TRANSCRIPT
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.
Working of stirling cryocoolerHot side (with heat sink) Cold side (cold finger)
Hot side
Cold side (cold finger)
• 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.