High-speed mid-infrared laser absorption spectroscopy of CO2 for shock-induced thermal non-equilibrium studies of planetary entry
Résumé
Abstract A high-speed laser absorption technique is employed to resolve spectral transitions of CO 2
2 in the mid-infrared at MHz rates to infer non-equilibrium populations/temperatures of translation, rotation and vibration in shock-heated CO 2
2 - Ar mixtures. An interband cascade laser (DFB-ICL) resolves 4 transitions within the CO 2
2 asymmetric stretch fundamental bands ( Δ
Δ v 3
3 = 1) near 4.19 \upmum
μ m . The sensor probes a wide range of rotational energies as well as two vibrational states (00 0
0 0 and 01 1
1 0). The sensor is demonstrated on the UCLA high enthalpy shock tube, targeting temperatures between 1250 and 3100 K and sub-atmospheric pressures (up to 0.2 atm). The sensor is sensitive to multiple temperatures over a wide range of conditions relevant to Mars entry radiation. Vibrational relaxation times are resolved and compared to existing models of thermal non-equilibrium. Select conditions highlight the shortcomings of modeling CO 2
2 non-equilibrium with a single vibrational temperature.
Domaines
Génie mécanique [physics.class-ph]
Fichier principal
Jelloian, Minesi, Spearrin - 2022 - High-speed mid-infrared laser absorption spectroscopy of CO2
for shock-induced thermal non-equi.pdf (3.7 Mo)
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