Cooling the GIFTS FPA: Summary and Analysis of Engineering Test Results Performed at SDL Using the Lockheed Martin Two-stage Cryocooler.

The Space Dynamics Laboratory (SDL), in partnership with NASA Langley Research Center is building the Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) instrument. This instrument will advance the current weather forecasting capability by studying the motion of water vapor in the atmosphere. The GIFTS focal plane assemblies (FPAs) must operate below 60 K to work properly. The spectrometer of the instrument which includes aft optics and an interferometer must operate below 150K. These two temperature zones will be cooled by a 2-stage pulse tube refrigerator built by Lockheed Martin. Prior to integration into the instrument, SDL performed extensive testing of the cyrocooler coupled to an ammonia loop heat pipe. This testing was done at SDL to characterize and validate the thermal and mechanical performance of the cryocooler. The thermal performance of the cryocooler as well as mechanical vibration characteristics observed during testing will be presented. This paper will discuss the challenges of designing, building, and integrating a cryocooler into a cryogenic instrument with very sensitive components, such as an interferometer, that can be adversely affected by mechanical vibrations in the system. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]