2018

Intra-pulse laser absorption sensor with cavity enhancement for oxidation experiments in a rapid compression machine

Intra-pulse laser absorption sensor with cavity enhancement for oxidation experiments in a rapid compression machine

E. F. Nasir, A. Farooq

Optics Express 26 (11), 14601-14609, 2018
E. F. Nasir, A. Farooq
Combustion diagnostics, Laser sensors, Absorption
2018


A sensor based on a mid-IR pulsed quantum cascade laser (QCL) and off-axis cavity enhanced absorption spectroscopy (OA-CEAS) has been developed for highly sensitive concentration measurements of carbon monoxide (CO) in a rapid compression machine. The duty cycle and the pulse repetition rate of the laser were optimized for increased tuning range, high chirp rate, and small line width to achieve effective laser-cavity coupling. This enabled spectrally resolved CO line-shape measurements at high pressures (P ~10 bar). A gain factor of 133 and a time resolution of 10 μs were demonstrated. CO concentration-time profiles during the oxidation of highly dilute n-octane/air mixtures were recorded, illustrating new opportunities in RCM experiments for chemical kinetics.
DOI: 10.1364/OE.26.014601