SPECTROSCOPIC EMISSION MEASUREMENTS WITHIN THE BLUNT-BODY SHOCK LAYERIN AN ARCJET FLOW

In the present study, radiation emanating from the freestream and shoc k-layer now over a 15.24-cm-diam, nat-faced cylinder model was measure d in the NASA Ames Research Center's 20-MW Arcjet Facility. The test g as 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. T he optical system was calibrated using tungsten and deuterium radiatio n 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, vibra tional, electronic temperatures, and species number densities within t he shock layer. An analysis was performed to estimate the uncertainty bounds of the determined properties.