Presentation on theme: "Active Coolers for cooling Infrared Detector on satellite payloads"— Presentation transcript:
1 Active Coolers for cooling Infrared Detector on satellite payloads Presentation ByMilind B NaikTIFR, MUMBAIStirling Cooler
2 Types of coolers Passive Coolers Active Coolers Radiators Stored CryogensActive CoolersStirling cycle (this presentation covers this cooler )Pulse tubeJoule-ThompsonBraytonAdiabatic Demagnetization3He coolersOptical coolingPeltier effect coolers
3 Passive Coolers Radiators Stored cryogens. Radiators are panels radiating heat according to Stefan's Lawextremely high reliabilitylow mass and a lifetime limited only by surface contamination and degradationlimitations on the heat load and temperature (typically in the milliwatt range at 70K )Multiple stages are often usedStored cryogens.Dewars containing a cryogen such as liquid helium or solid neonexcellent temperature stability with no exported vibrationssubstantially increases the launch mass of the vehiclelimit the lifetime of the mission to the amount of cryogen storedSTEPHANS LAW :AMOUNT FLUX FROM BLACK BODYFLUX : AMOUNT OF ENERGY / SECOND /SQ. CENIMETERITS MEASURE OF HOW BRIGHT SURFACE APPEARS.
4 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.
5 Advantages/disadvantages of different types of cooler technology
6 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 launchedor failed due to another component.Excluding electronics.STS/BETSE was a technology demonstrator.UARS/ISAMS figures per cooler running at 83% stroke.
14 Test-dewar for cryocooler testing Temperature SensorVacuum
15 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 assemblyCrycooler Fill and purge with HeliumVarious leak testsFunctional testsCalibrationsOthers.