Open AccessSensitive and rapid laser diagnostic for shock tube kinetics studies using cavity-enhanced absorption spectroscopy
Author(s) -
Kai Sun,
Shengkai Wang,
Ritobrata Sur,
Xing Chao,
Jay B. Jeffries,
Ronald K. Hanson
Publication year - 2014
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.22.009291
Subject(s) - optics , materials science , absorption (acoustics) , tunable diode laser absorption spectroscopy , spectroscopy , shock tube , laser , absorption spectroscopy , analytical chemistry (journal) , shock wave , tunable laser , chemistry , physics , chromatography , quantum mechanics , thermodynamics
We report the first application of cavity-enhanced absorption spectroscopy (CEAS) using a coherent light source for sensitive and rapid gaseous species time-history measurements in a shock tube. Off-axis alignment and fast scanning of the laser wavelength were used to minimize coupling noise in a low-finesse cavity. An absorption gain factor of 83 with a measurement time resolution of 20 µs was demonstrated for C2H2 detection using a near-infrared transition near 1537 nm, corresponding to a noise-equivalent detection limit of 20 ppm at 296 K and 76 ppm at 906 K at 50 kHz. This substantial gain in signal, relative to conventional single-pass absorption, will enable ultra-sensitive species detection in shock tube kinetics studies, particularly useful for measurements of minor species and for studies of dilute reactive systems.