High-pressure discharge lamps. Approaches to modelling

Two approaches to modelling high-pressure discharge lamps are discussed. 'Spectral' models attempt to predict a spectrum based on a one-dimensional (radial) treatment of the discharge with detailed atomic and molecular physics and radiative transport, but neglect two- and three-dimensional effects. 'Energy transport' models aim to predict the temperature distribution and flow patterns throughout the discharge tube in three dimensions, but simplify radiative transport and do not address the spectral prediction. The current trend of using commercially available modelling packages as the basis for three-dimensional lamp models is considered. Further progress will probably involve general energy transport models including heat transfer, fluid flow, electrical, magnetic and chemical effects; and local models to deal with more specialised phenomena such as electrode damage.