Use of cold radiometers in several thermal/vacuum tests

A low cost low temperature broadband radiometer has been developed for use with low temperature tests as a diagnostic tool for measuring stray thermal radiation and remote measurement of material properties. So far these radiometers have been used in three large thermal/vacuum tests for the James Webb Space Telescope (JWST) Project. In the first two tests the radiometers measured stray radiation in a test of part of the JWST sunshield, and in the third test the radiometers were used to measure the reflectivity and specularity of black ChemglazeTM Z307 painted aluminum walls on a 25 K cooled shroud. This paper will present the results of the reflectivity/specularity tests.