Characterization of NO Absorption Transitions for Magnetohydrodynamic Experiments at NASA HyMETS

This work presents scanned-wavelength laser absorption spectroscopy measurements (SW- LAS) of nitric oxide (NO) to support upcoming magnetohydrodynamic (MHD) flow control experiments in NASA’s HyMETS arc-jet facility. A tunable quantum cascade laser targeted two NO transitions near 1939.61 and 1939.79 cm⁻¹ behind reflected-shock conditions in the University of Central Florida (UCF) shock tube over temperatures ranging from 1200–2400 K. The measurements were used to characterize line-shape behavior, evaluate the suitability of these transitions for thermometry in arc-jet environments, and develop a full post- processing workflow for extracting temperature and species concentration. Measured absorbance was compared to HITEMP predictions to verify the accuracy of the line parameters under the tested conditions. These results establish the temperature dependence, absorption strength, and signal quality of the selected NO features, providing a validated basis for their use in future MHD control experiments in HyMETS.