Qualification of Pulse Tube Cryocooler for On-board Application − Thermal Aspects
A Pulse Tube Cryocooler (PTC) to meet a specification of 0.7W at 80K has been developed at ISAC for cooling Focal Plane assemblies (FPA) of IR detectors. The PTC developed is of the Stirling type having U − Tube configuration with a mass of ~ 4kg with an input of 54 watt. Subsequently, qualification tests for validating its space worthiness were initiated and successfully completed on the same. They include
EMI / EMC, pressure tests, vibration characterisation and Thermal tests.
This paper presents the details of the Thermal aspects of the qualification tests which include Humidity, thermal cycling and thermo-vacuum performance tests. Thermo-vacuum performance test
is one of the crucial aspect of cryocooler qualification as it addresses the issue of hermeticity of the pressurised Helium circuit in a vacuum environment, soundness of which is important to prevent failure of the unit from drop in pressure or loss of working fluid.
The tests also characterise the performance of various sub-assembly temperatures on the overall performance of the PTC.