Non-LTE modeling of high pressure sodium discharges

Summary form only given. In this work a non-equilibrium model is established to provide more accurate description of high pressure sodium-mercury-xenon plasma than the widely used standard LTE approaches. The core of the model consists of three time dependent balance equations in 1D cylindrical geometry: 1) Balance of electrons and ions. Quasi-neutrality is assumed, transport of electrons/ions is determined by ambipolar diffusion. 2) Energy balance of electrons. Careful attention is paid to clarify and include all important transport processes like heat conduction, Joule-heating, ionization/recombination heat, energy exchange with heavy particles. The energy balance is strongly influenced by sodium radiation, as well. Detailed radiative transfer is solved for all the important sodium lines. Several line broadening mechanisms like Na-Na, Na-Xe, Na-Hg interactions are included, too. As a result detailed radiation spectra are also provided by the calculations. 3) Energy balance of heavy particles. Ion/atom temperature is determined by energy exchange with electrons and heat conduction to the wall.