Spectroscopic measurements of nonequilibrium CO2 plasma in RF torch

This paper deals with the experimental study of the CO2 dissociation in a RF plasma torch at low pressure. Experiments have been carried out for different initial conditions in order to study the influence of the pressure and the power on the plasma characteristics. Furthermore the emission spectroscopic measurements have been performed at four different locations to investigate the evolution of the plasma chemistry from the creation zone to downstream. The results have confirmed that the CO2 plasma is in thermal and chemical nonequilibrium. For each condition, we have obtained the estimation of CO and O densities on their ground state from the chemiluminescent emission; and the rebuilding of experimental spectra has provided the species density on their excited states: O(3p5P), O(3p3P) and CO(B1Σ+). The discussion of the experimental data has led to make out a description of the chemical processes for the CO2 plasma under dissociation and has highlighted the main role of the vibrational excitation and relaxation on the kinetic mechanisms.