Nonequilibrium vibrational population measurements in an expanding flow using spontaneous Raman scatteringVibrational relaxation of nitrogen in a 2D nozzle flow is studied using spontaneous Raman scattering. An electric arc driven shock tube operating as a reflected shock tunnel produces stagnation conditions of 5600 K and 100 atm. A 248 nm KrF laser pulse is focused into the nozzle to produce spatially resolved spontaneous Raman spectra. Vibrational population distributions are derived from the spectra for the states v = 0 to v = 8. The experimental results are compared with two theoretical models: the Landau-Teller relaxation model and a numerical solution of the master equations using transition rates derived from SSH theory. The Landau-Teller correction factor has been measured at 1.0 - 1.5.
Document ID
19920065214
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Sharma, Surendra P. (NASA Ames Research Center Moffett Field, CA, United States)
Ruffin, Stephen M. (NASA Ames Research Center Moffett Field, CA, United States)
Gillespie, Walter D. (NASA Ames Research Center Moffett Field, CA, United States)
Meyer, Scott A. (Stanford University CA, United States)