Net emission coefficient of CO2-Cu thermal plasmas: role of copper and molecules.

Abstract

The present work was conducted to calculate the radiative transfer in CO2–Cu mixtures at atmospheric pressure. The plasma is supposed to be in local thermodynamic equilibrium (LTE) for temperatures between 500 and 30000 K. In the first part of the work, we briefly present the plasma composition. The second part is devoted to the various mechanisms responsible for the radiation (atomic continuum, molecular continuum, atomic lines and molecular bands). A particular attention is paid to the radiation of molecular bands. These radiative properties are then introduced in the net emission coefficient (NEC) which is used to estimate the radiation in an isothermal and homogeneous medium. Finally, some results are proposed for various concentrations of copper and different plasma sizes. For optically thin plasmas, the radiation of molecular bands and metallic vapors strongly increase the NEC at low temperature. For higher plasma sizes, the copper lines do not only have high intensities but are also strongly self-absorbed contrarily to the radiation of the molecular bands which becomes the major part, indicating that we must not neglect their contribution in the total radiation.