Abstract
A model is developed to calculate the emission spectrum of non-local thermodynamic equilibrium (LTE) plasmas. The collisional-radiative model is adopted for non-LTE population calculations. Configuration-averaged rate coefficients that are needed in the rate equations are obtained based on the first-order perturbation theory. The Hartree-Fock-Slater self-consistent-field method is used to calculate electron wavefunctions. The present model is applied to the calculation of isoelectronic line-ratio of Cr and Ti, which is useful for plasma electron temperature diagnosis.