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 • 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

neon .

– Dewars containing a cryogen such as liquid helium or solid – 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

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-dewarCrcycooler assembly – Crycooler Fill and purge with Helium – Various leak tests – Functional tests – Calibrations – Others.

Thanks …