Effects of Spacecraft Material Outgassing on Optical Systems in the Vacuum Ultraviolet

A new facility for measurement of transmittance as a function of contaminant thickness in the vacuum ultraviolet spectral region is described in this report. A series of tests were completed to validate the operation of the chamber and the spectral diagnostic systems. Transmittance of contaminant films deposited on a window were measured for five typical spacecraft materials. System performance met design specifications, with the exception of the signal to noise in the short wavenumber spectral range 115-130 nm. This problem resulted from the degradation of the deuterium source lamp output. The reduced output was caused by the accumulation of contaminants on the lamp window. Periodic cleaning of the lamp window can eliminate this problem.