Spectral measurement of nonequilibrium arc-jet free-stream flowSpectra of radiation emitted by the free-stream flow of air in an arcjet wind tunnel at NASA-Ames Research Center were studied experimentally. The arcjet produces a high energy gaseous flow that is expanded to low density and low temperature to produce high velocities in the free-stream for simulating atmospheric entry conditions. The gamma and the delta band systems of nitric oxide emitted by the free stream were measured in the second order. The NO-beta band system, which is in the same spectral region as the NO-gamma and NO-delta band systems, was not present in the data. Only transitions from the lowest vibrational level of the upper state of both the NO-gamma and NO-delta band systems were observed. The rotational temperature determined from these band systems was 660 +/- 50 deg K. The maximum possible vibrational temperature was determined to be less than 850 +/- 50 deg K. The electronic temperature determined from the ratio of the intensities of the NO-gamma and NO-delta band systems was 7560 +/- 340 K. The results indicate that the arcjet free-stream flow is in thermal nonequilibrium.
Document ID
19930070411
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Gopaul, Nigel K. J. M. (Stanford Univ. CA, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1993
Publication Information
Publication: In: International Instrumentation Symposium, 39th, Albuquerque, NM, May 2-6, 1993, Proceedings (A93-54351 24-35)