A Monte Carlo simulation of radiation trapping in electrodeless gas discharges having complex geometries

Summary form only given, as follows. Electrodeless gas discharges are finding increasing use as lighting sources due to their improved lifetimes compared to conventional hot cathode fluorescent lamps. As resonance radiation from the plasma is the source of excitation of the phosphors, radiation trapping is an important consideration in the design of these lamps. Conventional fluorescent lamps typically use simple cylindrical geometries for which analytic expressions for radiation trapping factors can be obtained. In more complex geometries and for conditions where the distribution of photon emitters and absorbers are not uniform, radiation trapping factors may have more complex dependencies. To investigate these processes, a Monte-Carlo radiation transport model has been developed and integrated into a plasma equipment model. The MC model accounts for frequency resolved radiation emission, transport and absorption while employting partial frequency redistribution. The plasma equipment model is a 2-dimensional, self consistent simulation including electromagnetics, electron energy transport, fluid equations for charge densities and solution of Poisson´s equation. Results will be discussed for the dependence of radiation trapping factors on pressure, power, geometry and gas mixture (temperature) for Ar/Hg mixtures in the 10s-100s mTorr range.