Ion composition of nitrogen plasma jet with carbon admixture

• Published in: Journal of physics. Conference series 2021-02, Vol.1787 (1), p.12063
• Main Authors: Kavyrshin, D I, Chinnov, V F, Korshunov, O V, Sargsyan, M A, Khromov, M A, Shcherbakov, V V
• Format: Article
• Language: English
• Subjects: Carbon; Decomposition reactions; Electron states; Impurities; Local thermodynamic equilibrium; Nitrogen; Nitrogen ions; Nitrogen plasma; Physics; Plasma; Plasma jets; Substitution reactions
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/1787/1/012063

With the aim of studying nitrogen plasma flow impacting graphite surfaces, we investigated the evolution of a plasma jet moving from the nozzle of the plasma torch to the target. The motion is accompanied by a decrease in temperature from 10 to 7 kK with a loss of ≈ 60% of the deposited energy and an increase in the density of carbon-containing impurities with partial preservation of the local thermodynamic equilibrium. The main reactions are thermal processes of the formation and decomposition of molecules, dissociative recombination and recharging of nitrogen ions. In the presence of carbon impurities, this set is supplemented with the substitution reaction C + N2 ↔ CN + N, electron-collision processes of stepwise ionization and recombination, and a whole ion-molecular cascades of reloads and substitutions. It has been established that a small admixture of carbon (∼ 0.1%) manifests itself only in ion-molecular kinetics, increasing the electron concentration, determining the ionic composition of the plasma, and thereby violating the equilibrium between its neutral and charged components. This leads, in particular, to the recombination nonequilibrium distribution of carbon atoms over electronic states. Other carbon-containing impurities (CN and C2) are not significant.