Calculation of spectral absorption coefficient of high temperature equilibrium or non-equilibrium 11-species air

As a reentry vehicle traveling through atmosphere with a very high Mach number, the ultraviolet, visible light and infrared signatures, produced from its head shock-wave layer and wake, are the foundation of detecting and identifying for the ground monitoring and the antimissile controlling and guiding system. At the same time, the gas layer radiation is also an important source of heating flux to the wall. The absorption coefficients of high temperature gas in the head shock-wave layer are basic parameters for calculations of the target ultraviolet, visible light and infrared optical characteristics, the heat shield and the aerodynamic flow-field coupling with thermal radiation. In this paper, after the thermo-chemical non-equilibrium phenomenon of hypersonic rarefied flow during reentry stage is discussed, a three-temperature model (electronic temperature T_e, vibrational temperature T_V and rotational-transitional temperature T_R) is used to characterize energy levels population of non-equilibrium air species in the shock-wave layer and the contribution of 11-species such as N₂, N₂⁺, N, N⁺, O₂, O₂⁺, O, O⁺, NO, NO⁺ and e^- is directly calculated by using the atomic and molecular radiation theory. At last, a model is established, which calculates the absorption coefficient of high-temperature equilibrium or non-equilibrium air. The results are in good agreement with experimentally measured data in the visible region, but are slightly bad in the ultraviolet and infrared regions.