Quantum cascade laser absorption sensor for carbon monoxide in high-pressure gases using wavelength modulation spectroscopy
Quantum cascade laser absorption sensor for carbon monoxide in high-pressure gases using wavelength modulation spectroscopy
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DOI：
10.1364/ao.53.001938
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发表时间：
2014-03-20
期刊：
影响因子：
1.9
通讯作者：
Hanson, R. K.
中科院分区：
文献类型：
--
作者：
Spearrin, R. M.;Goldenstein, C. S.;Hanson, R. K.
基于4.8 μ m波长调制吸收光谱技术，研制了一种可调谐量子级联激光传感器，用于测量高压苛刻燃烧气体中的CO浓度。该传感器采用归一化二次谐波检测技术（WMS - 2f /1f），调制频率为50 kHz。波长选择在2059.91 cm（-1）的目标是在CO的基本振动带内的P（20）跃迁，选择的吸收强度和相对隔离的红外水和二氧化碳吸收。CO光谱模型由Voigt线形函数定义，并且关键的线强度和线加宽光谱参数取自文献或测量。灵敏度分析确定的CO-N-2碰撞增宽系数作为最关键的不确定性缓解碳氢化合物/空气燃烧排气测量，这个参数是实验得出的燃烧温度范围内（1100-2600 K）在激波管中产生的。波长调制光谱传感器的准确性，使用精细的光谱模型，在压力大于40个大气压的非反应性冲击加热的气体混合物进行了验证。然后将激光器自由空间耦合到氟化铟单模光纤，用于远程光传输。该光纤耦合传感器在乙烯/空气脉冲爆震燃烧器上进行了演示，提供了恶劣流场中CO浓度的时间分辨（类似于20 kHz）原位测量。(C)2014年美国光学学会
A tunable quantum cascade laser sensor, based on wavelength modulation absorption spectroscopy near 4.8 mu m, was developed to measure CO concentration in harsh, high-pressure combustion gases. The sensor employs a normalized second harmonic detection technique (WMS - 2f /1f) at a modulation frequency of 50 kHz. Wavelength selection at 2059.91 cm(-1) targets the P(20) transition within the fundamental vibrational band of CO, chosen for absorption strength and relative isolation from infrared water and carbon dioxide absorption. The CO spectral model is defined by the Voigt line-shape function, and key line-strength and line-broadening spectroscopic parameters were taken from the literature or measured. Sensitivity analysis identified the CO-N-2 collisional broadening coefficient as most critical for uncertainty mitigation in hydrocarbon/air combustion exhaust measurements, and this parameter was experimentally derived over a range of combustion temperatures (1100-2600 K) produced in a shock tube. Accuracy of the wavelength-modulation-spectroscopy-based sensor, using the refined spectral model, was validated at pressures greater than 40 atm in nonreactive shock-heated gas mixtures. The laser was then free-space coupled to an indium-fluoride single-mode fiber for remote light delivery. The fiber-coupled sensor was demonstrated on an ethylene/air pulse detonation combustor, providing time-resolved (similar to 20 kHz), in situ measurements of CO concentration in a harsh flow field. (C) 2014 Optical Society of America