Nitrogen Atom Concentrations and Molecular Temperatures in Arc Jet Freestreams

Tribo Flow Separations, LLC proposes a novel method for measuring nitrogen ground state densities and rotational temperatures of molecular nitrogen in the free stream of arcjet ground testing facilities through emission spectroscopy measurements. Knowlede of these quantities will reduce uncertainties in the knowledge of local specific enthalpy which, in turn, is the defining quantity for the determination of heat flux to a surface of a probe or sample. In comparison with current methods, like Two Photon Laser Absorption Fluorescence, the proposed approach is cheaper than currently-used approaches by orders of magnitude, far easier to conduct and can be accomplished without interfering with other goals of testing; this aspect is of particular importance since no additional testing is required which saves testing costs. This new, unique method can be run as a standard diagnostic method without disrupting regular test schedules. It therefore provides the opportunity of monitoring test conditions very efficiently without relying on the stability of predefined test conditions, which in the end increases the reliability of the whole test campaign. Within Phase I, a single-channel, miniaturized spectrometer will be developed, constructed and used for its capability to measure nitrogen atom ground state densities and nitrogen molecule rotational temperatures. The foundational design of a multi-channel version will also be developed and then built, installed and tested at a NASA facility in Phase II.