Systematic observations of 150 W metal-halide arc lamps containing a progression of additive chemistries

Summary form only given. We examined a series of 150 W metal-halide arc lamps containing a progression of additive chemistries: 1) pure Hg, 2) Hg+HgI/sub 2/, 3) Hg+Nal, and 4) Hg+Nal+DyI/sub 3/. To minimize time-dependent effects, the lamps were driven by an electronic ballast. Comprehensive distributions of Hg densities were obtained by X-ray absorption imaging at the Advanced Photon Source/sup 2/, Argonne National Laboratory. Spatially-resolved elemental densities of Dy and I were obtained using X-ray induced fluorescence, also at the Advanced Photon Source. Spatially-resolved optical spectra over the range 3000 /spl Aring/ to 10,000 /spl Aring/ were obtained by Fourier transform spectroscopy. Self-reversed Hg emission lines were analyzed to determine core temperatures. The combination of temperature and Hg density yielded the lamp pressure according to the Ideal Gas Law. The spatially-resolved temperature in the remainder of each arc lamp were then found using the pressure and Hg density distribution obtained by X-ray absorption imaging. Molecular and atomic species densities have been calculated from thermo-chemical constants given the measured temperatures and elemental densities.