A vacuum compatible integrating sphere was built to operate inside a thermal vacuum chamber. This paper presents the
design and test results for a 1.65 meter diameter vacuum compatible integrating sphere with a 1.0 meter diameter exit
port and approximately 10kW of internal tungsten lamps. Liquid nitrogen is used as cooling medium to remove the heat
generated by these lamps. There are no moving parts inside the vacuum chamber.
The radiance is monitored with two filter-wheel detectors, one TE-cooled silicon and one TE-cooled germanium, as well
as a TE-cooled silicon array spectrometer. All three detectors are located outside the thermal vacuum chamber and view
the sphere radiance through fiber optic cables.
The system was tested inside a thermal vacuum chamber at NASA Goddard Space Flight Center before commissioning
in the 5.5 meter thermal vacuum chamber at Space Applications Centre in Ahmedabad, India. Results of tests of radiance
uniformity, radiance levels, and radiance stability are presented. Comparisons of the filter radiometers with the array
spectrometer are also presented.