Spectroscopic emission measurements within the blunt-body shock layer in an arcjet flow

In the present study, radiation emanating from the freestream and shock-layer now over a 15.24-cm-diam, nat-faced cylinder model was measured in the NASA Ames Research Center's 20-MW Arcjet Facility. The test gas was a mixture of argon and air. Spatially resolved emission spectra were obtained over a 200- to 890-nm wavelength range using a charged-coupled device camera (1024 x 256 array) attached to a spectrograph. The optical system was calibrated using tungsten and deuterium radiation sources. Analytical tools were used to determine the following line-of-sight-averaged thermodynamic properties from the calibrated spectra: 1) rotational temperature of the freestream and 2) rotational, vibrational, electronic temperatures, and species number densities within the shock layer. An analysis was performed to estimate the uncertainty bounds of the determined properties.