Using a collision-radiation model with extended excitation rates to calculate the OH spectrum in the ultraviolet band

Abstract

To improve the calculation accuracy of the ultraviolet (UV) nonequilibrium radiation spectrum in the plume and shock layer, an extended transition process collision-radiation model of hydroxyl (OH) is proposed. The transition processes for the vibrational level of the OH(A) state in the exchange reaction are extended, including both the fundamental band (Δν=1) and the universal band (Δν=2). Eight air components (N2, O2, H2, H2O, CO2, CO, H and O) are used instead of two components (N2 and O2) in the quenching and exchange reactions to make the extended model applicable to both a plume and shock layer. The accuracy of the extended model is verified by comparing the calculated number density for the OH(A) state of an Atlas III plume and the calculated spectral radiance of a BSUV-2 shock layer against experimental data. By comparing with the Atlas plume and error analysis, the results show that the calculated results of the extended C-R model are in better agreement with the experimental data than that of the original model. The accuracy of the developed spectral-line prediction model is higher than that the existing model, which is very important for research on target early warning, detection and recognition.