Metal halide lamps in the international space station ISS

Optical emission spectroscopy was performed on a metal-halide lamp under micro-gravity conditions of the international space station. Several transitions of atomic and ionic Dy and atomic Hg have been measured at different lateral positions from which we obtained atomic and ionic Dy and atomic Hg intensity profiles. After Abel inversion, the calibrated radial intensity profile of Hg was used to calculate a radial temperature profile. By combining the radial temperature profile with the calibrated radial intensity profile of the additive, the absolute radial density profile of the total atomic and ionic density of Dy was obtained. The measurements showed a hollow density profile for the atoms and ions in the centre. In the outer parts of the lamp molecules were found to dominate. Lamps containing Dy showed contraction of the arc, which increased for higher powers. Measurements were duplicated at 1-g and showed less radial segregation than for 0-g. As the power was increased, the difference between 0-g and 1-g of the radial intensity, density and temperature profile were diminished.