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
• 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.

Advantages/disadvantages of different types of cooler technology

•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)

Set of cold-finger available for 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.