Characterization of O atoms in the Plasmatron X Facility Free Jet via Spectrally Resolved Two Photon Laser Induced Fluorescence Imaging

In this work, we report progress on using non-intrusive, spectrally resolved nanosecond two-photon absorption laser-induced fluorescence (nsTALIF) strategies to probe oxygen (O) atoms in the University of Illinois Urbana-Champaign Plasmatron X Facility operating with an air plasma, aiming to better assess flow enthalpy. Measurements were conducted using an ICCD camera to take radial profile images of a tuned laser beam across the jet under various pressure and power conditions. The data presented here reveal encouraging trends in temperature, relative number density, and velocity, which are expected to complement future measurements of other species, such as nitric oxide (NO) and nitrogen (N) atoms. Comparisons with the latest numerical simulations are also provided, highlighting areas of agreement between the model and experiment, as well as identifying discrepancies that offer valuable guidance for future improvements. Near-term advancements, including improved energy normalization, better understanding of laser energy fluence limits, and refined laser linewidth estimates, are expected to help reduce uncertainties in the preliminary temperature and density results reported here.