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 e ow over a 15.24-cmdiam, e at-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 3 256 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 thermodynamicproperties 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.