Theoretical Investigation of CMH Lamps Ignition Properties in Ar/Hg Penning Gas Mixtures

Sz. Beleznai[1], I. Maros[2]
[1]Budapest University of Technology and Economics, Budapest, Hungary
[2]General Electric Lighting, GE Hungary KFT, Budapest, Hungary

Two-dimensional plasma transport model was developed in COMSOL Multiphysics Plasma Module to investigate fundamental issues in ceramic metal halide (CMH) lamps starting using Ar/Hg penning gas mixture. The intent of this work is to provide insight into possible design rules that might be applied to the improvement of start-up in moderate pressure metal halide lamps. The model gives a complete description of spatial- and time evolution of the discharge plasma. The overall characteristic derived from experimental data has been well described. The results indicate that the Penning effect has a strong influence on the breakdown voltage. At low Hg vapor pressure the results show significant voltage reduction at startup, while large partial pressures of mercury considerably deteriorate discharge ignition efficacy.