Prediction of spectra of high-pressure metal halide discharge lamps containing rare-earth fillings

In the development of high-pressure metal halide lamps there is a growing need for lamps with good color rendering properties. To meet these requirements rare-earth halides are added more often. Due to the multi-line atomic spectra of rare-earth species it is possible to fill the visible spectrum almost completely, which is the basis of the good color rendering properties of lamps containing rare-earth species. In order to support the development of such lamps numerical plasma models are being developed. These models and their verification require that good fundamental data is available for the radiative properties of the rare earth species. In this article an interpolation method is presented that can yield an indication of oscillator strengths of lines that are not known, based on a fit to a Boltzmann plot (log intensity against lower level energy), using oscillator strengths of lines that are already known to create the Boltzmann plot.