CO concentration measurements using tunable diode laser absorption spectroscopy behind the shock waves in Martian atmosphere

Xin Lin; Dachuan Li; Fei Li; Xilong Yu

doi:10.1117/12.2524261

29 March 2019 CO concentration measurements using tunable diode laser absorption spectroscopy behind the shock waves in Martian atmosphere

Xin Lin, Dachuan Li, Fei Li, Xilong Yu

Author Affiliations +

Proceedings Volume 11046, Fifth International Symposium on Laser Interaction with Matter; 110460A (2019) https://doi.org/10.1117/12.2524261
Event: Fifth International Symposium on Laser Interaction with Matter, 2018, Changsha, China

Abstract

Shock tube experiments are carried out to study the physical and chemical processes during a vehicle entry into the Mars atmosphere using tunable diode laser absorption spectroscopy (TDLAS) and optical emission spectroscopy (OES). CO concentration distributions are diagnosed behind a shock wave in a CO₂-N₂ mixture with three different conditions of initial pressure and velocity. The strong shock wave is established in a shock tube driven by combustion of hydrogen and oxygen. Time-resolved spectra of the Δv = 0 sequence of the B²Σ⁺ →X²Σ⁺ electronic transition of CN have been observed through OES. A precise analysis of the CN violet spectra is performed and used to determine rotational and vibrational temperatures. Two absorption lines in the first overtone band of CO near 2.33 μm, are selected from a HITRAN simulation to calibrate laser wavelength and detect the CO concentration. Combined with these temperature results using OES, CO concentrations in the thermal equilibrium region are derived, which are 2.91 × 10¹⁷ cm^-3, 7.46 × 10¹⁷ cm^-3 and 1.01 × 10¹⁸ cm^-3, corresponding to equilibrium temperatures equal to 7000 ± 400 K, 7400 ± 300 K, 6000 ± 300 K in the low, medium and high pressure conditions, respectively.

Citation Download Citation

Xin Lin, Dachuan Li, Fei Li, and Xilong Yu "CO concentration measurements using tunable diode laser absorption spectroscopy behind the shock waves in Martian atmosphere", Proc. SPIE 11046, Fifth International Symposium on Laser Interaction with Matter, 110460A (29 March 2019); https://doi.org/10.1117/12.2524261

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