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.

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 cryocoolerHot side (with heat sink) Cold side (cold finger)

Hot side

Cold side (cold finger)

Working of stirling cryocooler

Test-dewar for cryocooler testing

Test-dewar

Cryocooler

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 …