Glow-to-arc transitions in gas discharge lamps

The Waymouth model, which describes the glow-to-thermionic arc transition in qualitative terms, has been extended. To get a quantitative description of the glow-to-arc transition phenomena in metal halide lamps (with their emitterless electrodes) it is essential to include in the model a current dependent glow voltage. When this is done, the model calculations of the glow time and ignition time are found to agree well with experimental results. The influences of a number of lamp parameters on glow time and ignition time have been investigated in the light of this improved model.