Fiscal Year 1997

A prototype for an all fiber optic hydrogen sensor system was developed. Capability to measure concentrations of hydrogen in air or nitrogen in the range of 0.5 percent to 4.0 percent with a resolution of 0.1 percent was demonstrated. A DC planar magnetron sputter system was procured and assembled for use in the thin metal film deposition necessary for fabrication of the palladium and palladium-silver alloy sensors used in this development. A method was developed to coat the metal films with an organic coating permeable to hydrogen but not oxygen and other reactive gases. The results of tests on these sensors gave positive results but long-term studies are required to confirm protection under conditions expected to be encountered in a real world application. A new type of sensor base on a layered yttrium/palladium structure was constructed and tested. The greater magnitude and wavelength dependence of the spectral response observed may lead to a more robust sensor. However, the need to have oxygen present for this sensor in order for it to rapidly recover after exposure to hydrogen may complicate its use