Nonequilibrium plasma flow computation with atomic and molecular state transitions

A computational code for collisional-radiative rate equations coupled with momentum and energy conservation equations has been developed to study the effects of nonequilibrium atomic and molecular processes on the population densities in an air plasma flowfield. This model consists of fifteen air species: e^-, N, N⁺, N²⁺, O, O⁺, O²⁺, O^-, N₂, N⁺ ₂, NO, NO⁺, O₂, O⁺₂, and O^-₂ 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 ≤ 60,000 K. The state population, the chemical com-position and temperature profiles in a high enthalpy flow condition assuming the Fire II reentry problem are computed. Presented computational results indicated that the amount of radiative intensity emitted from nitrogen atoms has a possibility to be reduced more than 10 % due to the atomic and molecular state transitions.