Development of computational code for atomic and molecular processes in high enthalpy flow

In this study, a time-dependent collisional-radiative model for air plasma has been developed to study the effects of nonequilibrium atomic and molecular processes on population densities in a weakly ionized high enthalpy flow. This model consists of 15 species: e^-, N, N⁺, N²⁺, O, O⁺, O²⁺, O^-, N₂, N ₂⁺, NO, NO⁺, O₂, O₂ ⁺, and O₂^- with their major electronic excited states. Many elementary processes are considered in the number density range of 10¹²/cm³ ≤ N ≤ 10¹⁹/cm³ and the temperature range of 300 K ≤ T ≤ 40,000 K. We then compute the unsteady nature of pulsively heated air plasma. When the ionization relaxation time is the same order as the time scale of a heating pulse, the effects of unsteady ionization are important for estimating air plasma states.