Modeling chemical reactions in laser-induced plasmas

Under the assumption of local thermal equilibrium, a numerical algorithm is proposed to find the equation of state for laser-induced plasmas (LIPs) in which chemical reactions are permitted in addition to ionization processes. The Coulomb interaction in plasma is accounted for by the Debye–Huckel method. The algorithm is used to calculate the equation of state for LIPs containing carbon, silicon, nitrogen, and argon. The equilibrium reaction constants are calculated using the latest experimental and ab initio data of spectroscopic constants for the molecules $$\hbox {N}_2, \hbox {C}_2, \hbox {Si}_2, \hbox {CN}, \hbox {SiN}, \hbox {SiC}$$ and their ions. The algorithm is incorporated into a fluid dynamic numerical model based on the Navier–Stokes equations describing an expansion of LIP plumes into an ambient gas. The dynamics of LIP plumes obtained by the ablation of SiC, solid silicon, or solid carbon in an ambient gas containing $$\hbox {N}_2$$ and Ar is simulated to study formation of molecules and molecular ions.