研究目的
Investigating the spectroscopic modeling of oxygen absorption cross-sections in the Schumann-Runge system for non-equilibrium conditions using a tunable, pulsed UV laser.
研究成果
The study demonstrated the efficacy of using a tunable, pulsed UV laser diagnostic with a spectroscopic model to measure oxygen absorption cross-sections in non-equilibrium conditions. The experimental cross-sections agreed within 15% of the Stanford model predictions, validating the model's accuracy. This approach can be extended to extract vibrational state-specific population time histories of oxygen in hypersonic environments.
研究不足
The study is limited by the assumption of vibrational temperature reaching the post-shock translational temperature for conditions below 6,000 K and the steady-state approach for higher temperatures. The effects of dissociation on cross-section measurements were mitigated but not entirely eliminated.
1：Experimental Design and Method Selection:
The study utilized a shock tube augmented with a tunable, pulsed UV laser system to measure cross-sections of shock-heated oxygen (O2) in argon (Ar) mixtures. The spectroscopic model (Stanford model) was developed to simulate oxygen absorption cross-sections.
2：Sample Selection and Data Sources:
Measurements were taken behind reflected shocks in 2% and 5% O2 in Ar mixtures around 211.2 nm and 236.9 nm up to initial post-reflected shock temperatures of 10,700 K.
3：2 nm and 9 nm up to initial post-reflected shock temperatures of 10,700 K.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: A shock tube, a tunable, pulsed UV laser system, and optical detectors were used. The shock tube was filled with pure helium in the driver section and dilute O2 in Ar mixtures in the driven section.
4：Experimental Procedures and Operational Workflow:
The shock tube was evacuated before each experiment. The UV laser was focused into the shock tube, and absorbance measurements were taken behind reflected shocks. Vibrational temperatures were calculated using a Bethe-Teller relaxation model and a steady-state approach.
5：Data Analysis Methods:
The experimental cross-sections were compared to calculated cross-sections from the Stanford model and the Adjusted Spectrum model. The agreement between models and data was analyzed.
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