Vibrational temperature from measurements of N2 and N2(+) shock layer radiation

Measurements of the vibrational temperature in a shock layer produced by a cylindrical blunt body in an arc jet nitrogen flow are made for both the neutral molecule and the molecular ion. Spectra were obtained at two locations in the shock layer produced by a 20-cm long cylindrical blunt body inserted in the arc jet conical flow. The technique used for determining the temperatures from the spectral radiation involves obtaining ratios of integrated intensities for certain spectral regions of the measured spectrum and making a comparison with computed ratios as a function of temperature for the same spectral regions. The technique is difficult to apply due to radiation overlapping bands from other species. However, using a trial and error procedure, the vibrational and rotational temperatures at the two locations are inferred. The results indicate that the shock layer is significantly out of thermal equilibrium.