Characterization of N₂/CH₄ Plasma Emission
Résumé
Emission measurements of a high-temperature N2/CH4/Ar plasma are presented. A plasma torch is used to generate a N2/CH4/Ar plasma near local thermodynamic equilibrium (LTE) at atmospheric pressure and a temperature of 7000 K. The LTE plasma is then rapidly cooled by passing it at high speed through a water-cooled tube. The rapid cooling initiates chemical recombination. The evolution of the thermochemical properties of the plasma is studied experimentally as it flows through the water-cooled tube. Optical Emission Spectroscopy (OES) measurements between 320 – 880 nm are presented. The spectra are calibrated in absolute intensity and wavelength and provide direct measurements of the CN excited states densities and their vibrational population distributions. Spectral analysis is done using the SPECAIR line-by-line radiative code and the Exomol trihybrid radiative database. The data obtained from experimental measurements is compared to models present in the literature describing the N2/CH4 plasma recombination kinetics.