Development of rotational CARS for combustion diagnostics using a polarization approach

Vestin, Fredrik; Afzelius, Mikael; Bengtsson, Per-Erik

doi:10.1016/j.proci.2006.07.066

Cited by 39 publications

(23 citation statements)

References 36 publications

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“…Considering these equations allows calculation of the polarization state of the CARS wave and its dependence on the incident field polarization states. These relationships have been utilized to find relative orientations of the input beam polarization states to suppress either the elastically scattered laser light [137] or the non-resonant signal contributions which are usually difficult to quantify [138]. In the following however we consider the simplest situation, i.e., when the polarizations of all lasers and as a consequence the signal polarization are parallel.…”

Section: Theory Of Carsmentioning

confidence: 99%

“…In order 72 to overcome this problem two potential approaches have been developed. Firstly, the tensor nature of the susceptibility allows the dependence of the signal polarization on the polarizations of the incident laser beams to be exploited in order to suppress the non-resonant background [138,163,164]. A second possibility is to use short-pulse lasers in the pico-…”

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confidence: 99%

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Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Kiefer

Ewart

2011

Progress in Energy and Combustion Science

131

112

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Laser-based methods have transformed combustion diagnostics in the past few decades. The high intensity, coherence, high spectral resolution and frequency tunability available from laser radiation has provided powerful tools for studying microscopic processes and macroscopic phenomena in combustion by linear and nonlinear optical processes. This review focuses on nonlinear optical techniques based on resonant four-wave mixing for non-intrusive measurements of minor species in combustion. The importance of minor species such as reaction intermediates is outlined together with the challenges they present for detection and measurement in the hostile environments of flames, technical combustors, and engines. The limitations of conventional optical methods for such measurements are described and the particular advantages of coherent methods using nonlinear optical techniques are discussed.The basic physics underlying four-wave wave mixing processes and theoretical models for signal calculation are then presented together with a discussion of how combustion parameters may be derived from analysis of signals generated in various four-wave mixing processes. The most important four-wave mixing processes, in this context, are then reviewed:Degenerate Four-Wave Mixing (DFWM), Coherent Anti-Stokes Raman Scattering (CARS), Laser Induced Grating Spectroscopy (LIGS) and Polarization Spectroscopy (PS). In each case the fundamental physics is outlined to explain the particular properties and diagnostic advantages of each technique. The application of the methods mentioned to molecular physics studies of combustion species is then reviewed along with their application in measurement of concentration, temperature and other combustion parameters. Related nonlinear techniques and recent extensions to the ultra-fast regime are briefly reviewed. Finally practical considerations relevant to multi-dimensional and multi-species measurements, as well as applications in technical combustion systems are discussed.Keywords: nonlinear optical spectroscopy, four-wave mixing, combustion diagnostics, minor species detection, laser-induced gratings, polarization spectroscopy IntroductionEnergy from renewable sources such as solar and wind power is the goal of much current research and technological development. Combustion, however, is and is likely to remain for the foreseeable future, the most important energy source for heat, electrical power and especially for transportation. In technical combustion systems the chemical energy of fossil fuels such as coal, crude oil and natural gas is converted into heat through oxidation with oxygen from air. However, fossil fuel resources are limited and alternatives like biofuels [1] or novel technologies such as fuel cells [2] are not yet able to meet the demand. Consequently, for a sustainable use of fossil fuels it is desirable to further improve the efficiency, maintainability and reliability of existing combustion devices. Achieving such improvements depends upon an improved understanding of t...

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Section: Theory Of Carsmentioning

confidence: 99%

mentioning

confidence: 99%

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Kiefer

Ewart

2011

Progress in Energy and Combustion Science

131

112

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“…By the formalism developed in Ref. 22, it can be shown that polarization gating alone results in a reduction of the resonant CARS signal by 44%.…”

Section: Alexis Bohlinmentioning

confidence: 99%

“…The time-resolved approach also provides an efficient method to suppress the non-resonant background, 20 which otherwise may impose a great challenge within CARS and microscopy. Multiple strategies have been developed [21][22][23][24] to suppress the nonresonant signal contributions.…”

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confidence: 99%

Single-shot hyperspectral coherent Raman planar imaging in the range 0–4200 cm−1

Bohlin

Kliewer

2014

Applied Physics Letters

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We propose a technique for ultrabroadband planar coherent Raman spectroscopy that enables wideband chemically selective mapping of molecular partition functions in the gas-phase within a single-laser-shot. A spectral region spanning 0–4200 cm−1 is excited simultaneously, in principle allowing for coherent planar imaging of most all fundamental Raman-active modes. This unique instantaneous and spatially correlated assessment enables multiplexed studies of transient dynamical systems in a two-dimensional (2D) field. Here, we demonstrate single-laser-shot high temperature diagnostics of H2, with spatially resolved 2D measurement of transitions of both the pure-rotational H2 S-branch and the vibrational H2 Q-branch, analyzing the temperature contour of a reacting fuel-species as it evolves at a flame-front.

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“…While CARS offers excellent chemical specificity and efficient signal collection, measurement errors from composition-dependent interferences, such as collisional energy transfer and nonresonant background, significantly complicate the analysis, particularly in high-pressure environments [2]. As shown in previous work, interferences from nonresonant background can be suppressed in the frequency domain using polarization techniques [3] or by temporally separating the probe pulse from the pump and Stokes pulses [4][5][6]. Temporal suppression has been demonstrated for both vibrational [7] and rotational CARS [8], but the temporal probe delays in previous work were sufficiently long (~100 ps) that the rovibrational and rotational spectra were sensitive to the effects of collisions on individual rotational transitions, especially at low temperature.…”

Section: Introductionmentioning

confidence: 96%

Interference-free gas-phase thermometry at elevated pressure using hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering

Miller¹,

Dedic²,

Roy³

et al. 2012

Opt. Express

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Rotational-level-dependent dephasing rates and nonresonant background can lead to significant uncertainties in coherent anti-Stokes Raman scattering (CARS) thermometry under high-pressure, lowtemperature conditions if the gas composition is unknown. Hybrid femtosecond/picosecond rotational CARS is employed to minimize or eliminate the influence of collisions and nonresonant background for accurate, frequency-domain thermometry at elevated pressure. The ability to ignore these interferences and achieve thermometric errors of <5% is demonstrated for N 2 and O 2 at pressures up to 15 atm. Beyond 15 atm, the effects of collisions cannot be ignored but can be minimized using a short probe delay (~6.5 ps) after Raman excitation, thereby improving thermometric accuracy with a time-and frequency-resolved theoretical model. KeywordsFriedrich-Alexander University Erlangen, Raman scattering, Raman spectroscopy, dephasing rates, elevated pressure, femtoseconds, frequency domains, gas compositions, gasphase, low temperatures, nonresonant, Raman excitation, chemistry, computer aided design, phase transition, radiation scattering, thermography, computer-aided design, equipment design Disciplines Chemistry | Mechanical Engineering CommentsThis article is from Optics Express 15 (2012): 5003, doi: 10.1364/OE.20.005003. Posted with permission. RightsThis paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on tahe OSA website: https://www.osapublishing.org/ oe/abstract.cfm?uri=oe-20-5-5003. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law. Abstract: Rotational-level-dependent dephasing rates and nonresonant background can lead to significant uncertainties in coherent anti-Stokes Raman scattering (CARS) thermometry under high-pressure, lowtemperature conditions if the gas composition is unknown. Hybrid femtosecond/picosecond rotational CARS is employed to minimize or eliminate the influence of collisions and nonresonant background for accurate, frequency-domain thermometry at elevated pressure. The ability to ignore these interferences and achieve thermometric errors of <5% is demonstrated for N 2 and O 2 at pressures up to 15 atm. Beyond 15 atm, the effects of collisions cannot be ignored but can be minimized using a short probe delay (~6.5 ps) after Raman excitation, thereby improving thermometric accuracy with a time-and frequency-resolved theoretical model. ©2012 Optical Society of America

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Development of rotational CARS for combustion diagnostics using a polarization approach

Cited by 39 publications

References 36 publications

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Single-shot hyperspectral coherent Raman planar imaging in the range 0–4200 cm−1

Interference-free gas-phase thermometry at elevated pressure using hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering

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