Study of Radiation in Electric Arc Shock Tubes

In a recent article, Cruden et al. reviewed recent updates to the NASA Ames Electric Arc Shock Tube (EAST) facility. This was prompted because of discrepancies in predictions based on equilibrium assumptions and measured spectral radiance, and because of the presence of impurities in the facility which were not accounted for in the computations. As a result of updates, it is now possible to obtain four simultaneous spectrographic images at the same tube axial location during a single test in the wavelength range 1200-17000 A. In addition, repeatability of the shock velocity is around 1% compared to 5% of earlier measurements. Further, a reduction of the carbon and hydrogen contaminants has been achieved. In an earlier investigation, time-accurate calculations of the ow eld in the shock tube were carried out using NASA Ames Navier-Stokes solver DPLR. The ow was assumed to be in thermal and chemical nonequilibrium. The investigation was focused on conditions typical of peak heating for lunar return that take place at about 0.2 torr and 10 km=s. NEQAIR2009 was then used with the computed ow eld to calculate the spectral radiances for the wavelength ranges considered in the experiment.