Dual-pump vibrational/rotational femtosecond/picosecond coherent anti-Stokes Raman scattering temperature and species measurements

Dedic, Chloe E.; Miller, Joseph D.; Meyer, Terrence R.

doi:10.1364/ol.39.006608

Cited by 49 publications

(22 citation statements)

References 21 publications

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“…The great flexibility of the CARS technique makes it a popular instrument for performing thermometry measurements for various gases: nitrogen and oxygen [11][12][13], carbon dioxide [14], as well as methane and hydrogen [15]. CARS techniques allow concentration and temperature measurements in harsh environments and at high temperature during the combustion process [16,17].…”

Section: Introductionmentioning

confidence: 99%

Collinear FAST CARS for Chemical Mapping of Gases

et al. 2017

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Featured Application: remote spectroscopic mapping of gas emissions and leaks. Abstract:We examine the concentration dependence of the Coherent Anti-Stokes Raman Scattering (CARS) signal obtained for gas mixtures at various conditions using the Femtosecond Adaptive Spectroscopic Technique (FAST). We use the CARS signal of the Q-branch vibrational oscillation of molecular oxygen (1556 cm −1 ) to confirm the quadratic dependence of the coherent signal on the number of molecules in a test volume. In addition, we demonstrate multi-shot FAST CARS imaging of a gas flow in free space by raster-scanning the area of interest.

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Section: Introductionmentioning

confidence: 99%

Collinear FAST CARS for Chemical Mapping of Gases

et al. 2017

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“…Unfortunately, single-shot thermometry was limited to temperatures below T = 800 K because the majority of the available probe-beam energy was discarded with the bandwidth, starving the CARS instrument of the probe-pulse energy required to generate sufficient signal in high-temperature environments. Flame thermometry via fs/ps rotational CARS was very recently demonstrated up to T = 1500 K by Dedic et al [35], albeit by averaging of the signal over many laser shots.…”

Section: Introductionmentioning

confidence: 99%

“…Femtosecond sources provide nearly transform-limited pump and Stokes pulses, whose large bandwidth and well-defined spectral phase relationship allow for highly efficient [9] preparation of the Raman coherence with very low noise, which has resulted in single-shot temperature-measurement precision in flames as good as 1% [24] when vibrational CARS of N 2 has been employed. http Pure-rotational CARS provides distinct advantages for combustion monitoring and has been the subject of recent development [14,15,[17][18][19][20][21][22]27,[33][34][35][36][37] for use with femtosecond pump/Stokes laser schemes. Rotational Raman spectra are a highly sensitive thermometer over a wide range of temperatures [38][39][40], and offer a potentially straightforward approach to simultaneous species detection because rotational transitions of many combustionrelevant molecules (N 2 , O 2 , CO, CO 2 ) lie below $300 cm À1 and are accessible with a single broadband laser source [41,42].…”

Section: Introductionmentioning

confidence: 99%

Hybrid fs/ps rotational CARS temperature and oxygen measurements in the product gases of canonical flat flames

Kearney

2015

Combustion and Flame

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a b s t r a c tA hybrid fs/ps pure-rotational coherent anti-Stokes Raman scattering (CARS) scheme is systematically evaluated over a wide range of flame conditions in the product gases of two canonical flat-flame burners. Near-transform-limited, broadband femtosecond pump and Stokes pulses impulsively prepare a rotational Raman coherence, which is later probed using a high-energy, frequency-narrow picosecond beam generated by the second-harmonic bandwidth compression scheme that has recently been demonstrated for rotational CARS generation in H 2 /air flat flames. The measured spectra are free of collision effects and nonresonant background and can be obtained on a single-shot basis at 1 kHz. The technique is evaluated for temperature/oxygen measurements in near-adiabatic H 2 /air flames stabilized on the Hencken burner for equivalence ratios of u = 0.20-1.20. Thermometry is demonstrated in hydrocarbon/air products for u = 0.75-3.14 in premixed C 2 H 4 /air flat flames on the McKenna burner. Reliable spectral fitting is demonstrated for both shot-averaged and single-laser-shot data using a simple phenomenological model. Measurement accuracy is benchmarked by comparison to adiabatic-equilibrium calculations for the H 2 /air flames, and by comparison with nanosecond CARS measurements for the C 2 H 4 /air flames. Quantitative accuracy comparable to nanosecond rotational CARS measurements is observed, while the observed precision in both the temperature and oxygen data is extraordinarily high, exceeding nanosecond CARS, and on par with the best published thermometric precision by femtosecond vibrational CARS in flames, and rotational femtosecond CARS at low temperature. Threshold levels of signal-to-noise ratio to achieve 1-2% precision in temperature and O 2 /N 2 ratio are identified. The results show that pure-rotational fs/ps CARS is a robust and quantitative tool when applied across a wide range of flame conditions spanning lean H 2 /air combustion to fuel-rich sooting hydrocarbon flames.

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“…Methods have been demonstrated which improve the accuracy and precision of hybrid fs/ps-CARS to levels similar to those of vibrational fs-CARS over a wide range of temperatures, 298-2400 K [21,23] . The hybrid technique has also proven useful for accurate relative concentration measurements [24,25] .…”

Section: Introductionmentioning

confidence: 99%

5 kHz thermometry in a swirl-stabilized gas turbine model combustor using chirped probe pulse femtosecond CARS. Part 1: Temporally resolved swirl-flame thermometry

Dennis

Slabaugh

Boxx

et al. 2016

Combustion and Flame

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a b s t r a c tSingle-laser-shot temperature measurements at 5 kHz were performed in a gas turbine model combustor using femtosecond (fs) coherent anti-Stokes Raman scattering (CARS). The combustor was operated at two conditions; one exhibiting a low level of thermoacoustic instability and the other a high level of instability. Measurements were performed at 73 locations within each flame in order to resolve the spatial flame structure and compare to previously published studies. The measurement procedures, including the procedure for calibrating the laser system parameters, are discussed in detail. Despite the high turbulence levels in the combustor, signals were obtained on virtually every laser shot, and these signals were strong enough for spectral fitting analysis for determination of flames temperatures. The spatial resolution of the single-laser shot temperature measurements was approximately 600 μm, the precision was approximately ±2%, and the estimated accuracy was approximately ±3%. The dynamic range was sufficient for temperature measurements ranging from 300 K to 2200 K, although some detector saturation was observed for low temperature spectra. These results demonstrate the usefulness of fs-CARS for the investigation of highly turbulent combustion phenomena. In a companion paper, the time-resolved fs CARS data are analyzed to provide insight into the temporal dynamics of the gas turbine model combustor flow field.

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Dual-pump vibrational/rotational femtosecond/picosecond coherent anti-Stokes Raman scattering temperature and species measurements

Cited by 49 publications

References 21 publications

Collinear FAST CARS for Chemical Mapping of Gases

Collinear FAST CARS for Chemical Mapping of Gases

Hybrid fs/ps rotational CARS temperature and oxygen measurements in the product gases of canonical flat flames

5 kHz thermometry in a swirl-stabilized gas turbine model combustor using chirped probe pulse femtosecond CARS. Part 1: Temporally resolved swirl-flame thermometry

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