Collisional-radiative modeling of free-burning arc plasma in argon

Recent ambitions have been aimed at improving a free-burning arc modeling by means of a self-consistent description of the arc plasma and the electrodes avoiding assumptions of equilibrium. As next step, the present work is dealing with the impact of the reaction chemistry used in non-equilibrium modelling of free-burning arc in argon. A simple chemistry model based on the approximation of prompt ionization, a model with an effective excited level, and a model implying higher excited levels of argon atoms are considered. The results obtained show that all three models are capable of predicting the arc characteristics. They deliver values of electric current density, electric conductivity, arc voltage, electron and heavy particle temperature which are close to each another. The simple model can serve as a fast track evaluation of the arc characteristics, and for sensitive studies of the impact of model parameters. The extended model allows obtaining the populations of individual and effective levels giving rise to important radiative transitions and enables comparisons with spectroscopic measurements.