Temperature measurement by single-shot dual-line CARS in low-pressure flows

Péalat, M.; Lefebvre, M.

doi:10.1007/bf00325478

Cited by 32 publications

(3 citation statements)

References 11 publications

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“…Such simultaneous referencing was used previously in dual-line CARS. 40,41 There the signal from pump beams focused in a reference cell was measured simultaneously with the resonant signal in the device under study to reduce systematic errors and noise. Because the reference signal is created by a CARS process as well, it compensates for intensities, beam aberrations, and beam overlap.…”

Section: Referencingmentioning

confidence: 99%

“…But, because each excitation profile may be considered unique, it would be best if the applied excitation profile were to correspond exactly to the profile that generates the single-shot N 2 spectrum. To reach this goal, in dual-line CARS 40,41 shotby-shot referencing was arranged by use of a reference cell or oven in series or in parallel with the flame or flow under study. To reduce noise it is important to ascertain that the two spectra monitor equivalent spectral intervals and that the same fluctuations contribute to the nonresonant reference spectrum as to the resonant spectrum.…”

Section: Introductionmentioning

confidence: 99%

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Thermometry for turbulent flames by coherent anti-Stokes Raman spectroscopy with simultaneous referencing to the modeless excitation profile

Veen

Roekaerts

2005

Appl. Opt.

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An optimal system for temperature measurements by coherent anti-Stokes Raman spectroscopy (CARS) in turbulent flames and flows is presented. In addition to a single-mode pump laser and a modeless dye laser, an echelle spectrometer with a cross disperser is used. This system permits simultaneous measurement of the N 2 CARS spectrum and the broadband dye laser profile. A procedure is developed to use software to transform this profile into the excitation profile by which the spectrum is referenced. Simultaneous shot-to-shot referencing is compared to sequential averaged referencing for data obtained in flat flames and in room air. At flame temperatures, the resultant 1.5% imprecision is limited by flame fluctuations, indicating that the system may have a single-shot imprecision below 1%. At room temperature, the 3.8% single-shot imprecision is of the same order as the best values reported for dualbroadband pure-rotational CARS. Using the unique shot-to-shot excitation profiles, simultaneous referencing eliminates systematic errors. At 2000 and 300 K, the 95% confidence intervals are estimated to be Ϯ20 and Ϯ10 K, respectively.

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Section: Referencingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermometry for turbulent flames by coherent anti-Stokes Raman spectroscopy with simultaneous referencing to the modeless excitation profile

Veen

Roekaerts

2005

Appl. Opt.

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“…Laser-induced fluorescence ͑LIF͒, 13,14 linear Raman spectroscopy, 11,[15][16][17][18] nonlinear Raman spectroscopy, [19][20][21][22][23] and third-harmonic nonlinear generation, 24,25 have proved efficient for the attainment of rotational and vibrational temperatures in a wide spatial domain of the jet. Rayleigh scattering, combined with linear Raman spectroscopy, has provided a measure of the density number in the jet.…”

Section: Introductionmentioning

confidence: 99%

Raman spectroscopy of supersonic jets of CO2: Density, condensation, and translational, rotational, and vibrational temperatures

Maté¹,

Tejeda²,

Montero³

1998

The Journal of Chemical Physics

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Raman spectroscopy and crystal-field split rotational states of photoproducts CO and H2 after dissociation of formaldehyde in solid argon J. Chem. Phys. 137, 164310 (2012) The links between translational, rotational, and vibrational temperatures of supersonic molecular jets, and their density and degree of condensation, are discussed in terms of quantitative Raman scattering experimental data. Such links are established as the result of energy and momentum conservation laws, and of the collisional regime in the jet. Four representative supersonic expansions of CO 2 , generated at different stagnation pressures are analyzed, showing the potential of quantitative Raman spectroscopy for a complete characterization of the jet.

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Saturation and Stark broadening effects in dual‐pump CARS of N₂, O₂, and H₂

Magnotti

Cutler

Herring

et al. 2012

J Raman Spectroscopy

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The dual-pump coherent anti-Stokes Raman spectroscopy (CARS) technique is frequently employed in the study of turbulent flames, but the applicability of this technique is limited by low signal-to-noise ratios at high temperatures. The signal-to-noise ratio can be increased by increasing the energy of the lasers. Unfortunately, there is a limit to the amount of energy that can be added before the signal is affected by high irradiance perturbation effects such as Stark broadening and stimulated Raman pumping (saturation). Such effects alter the spectral shape of the CARS signal and compromise the measurement accuracy. To explore these effects, dual-pump CARS spectra containing the N 2 and O 2 Q-branch manifolds and three S-branch H 2 rotational lines were acquired in H 2 -air flames while varying the irradiances of the different input beams. For fuel-lean flames at 1180 K and 1 atm., absolute mole fraction measurements are affected by Stark broadening when the total irradiance is above 250 GW/cm 2 , and by saturation when the product of the pump and Stokes irradiances is above 2 Â 10 3 GW 2 /cm 4 . The H 2 S-branch is more sensitive to Stark broadening, and small variations in the line amplitude are observed for total irradiance of 170 GW/cm 2 . Temperature measurements are not sensitive to Stark broadening, but they are affected by saturation when the pump-Stokes irradiances product is above 2 Â 10 4 GW 2 /cm 4 .

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Temperature measurement by single-shot dual-line CARS in low-pressure flows

Cited by 32 publications

References 11 publications

Thermometry for turbulent flames by coherent anti-Stokes Raman spectroscopy with simultaneous referencing to the modeless excitation profile

Thermometry for turbulent flames by coherent anti-Stokes Raman spectroscopy with simultaneous referencing to the modeless excitation profile

Raman spectroscopy of supersonic jets of CO2: Density, condensation, and translational, rotational, and vibrational temperatures

Saturation and Stark broadening effects in dual‐pump CARS of N₂, O₂, and H₂

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Temperature measurement by single-shot dual-line CARS in low-pressure flows

Cited by 32 publications

References 11 publications

Thermometry for turbulent flames by coherent anti-Stokes Raman spectroscopy with simultaneous referencing to the modeless excitation profile

Thermometry for turbulent flames by coherent anti-Stokes Raman spectroscopy with simultaneous referencing to the modeless excitation profile

Raman spectroscopy of supersonic jets of CO2: Density, condensation, and translational, rotational, and vibrational temperatures

Saturation and Stark broadening effects in dual‐pump CARS of N2, O2, and H2

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Saturation and Stark broadening effects in dual‐pump CARS of N₂, O₂, and H₂