Modeling of metal halide lamps

Summary form only given. The modeling of arcs in metal halide lamps presents a number of formidable problems. Due to the complex chemistry in current MH lamps, the arc may contain hundreds of different chemical species and emit thousands of spectral lines. The acquisition of reliable data for the chemical and thermodynamic and spectral properties of the most important species is the subject of experimental programs throughout the world. Further, the geometry of MH lamps is sufficiently complex to require 2D or 3D models. In order to obtain meaningful results, therefore, a number of compromises need to be made in order to reduce the problem to a manageable one. In this presentation, the current status of MH arc modeling are reviewed. Topics discussed include radiation transport, de-mixing of chemical species due to diffusion processes, joule heating of the arc and the influence of electrodes. The importance of the development of numerical models in conjunction with the evaluation of available data and validation of results by diagnostic techniques such as spectral measurements is stressed. The work concludes with a number of challenges which need to be met if the next generation of MH arc models is to provide a useful guide to the development of new and improved light sources.