Derivation of species distribution in inductively heated CO2 plasma via automated spectral fitting

Abstract

To investigate the dissociation and recombination processes in a plasma jet, the characterization of its composition is important. For this purpose, an automated fitting algorithm for emission spectroscopic measurements, based on the radiation simulation tool PARADE, is developed. The algorithm is demonstrated by qualitatively analyzing single carbon dioxide spectra of the inductive plasma generator IPG4, operated at 125kW anode power with a CO2 mass flow rate of 2.2g/s. The species O, C, CO, CO+, CN and C2 are fitted with regards to number density, as well as vibrational and rotational temperature. A radial analysis of species composition is performed at two axial positions in the plasma jet. The results show different regions inside the plasma, suggesting increasing CO dissociation towards the centerline, as well as recombination of atomic carbon with molecular nitrogen. Moreover, the species composition distribution is found to be an indicator for the flow conditions in underexpanded free turbulent plasma jets.