23 May 1997 Combustion diagnostic using degenerate four wave mixing spectroscopy
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Proceedings Volume 3108, Combustion Diagnostics; (1997); doi: 10.1117/12.274762
Event: Environmental Sensing III, 1997, Munich, Germany
Abstract
The DFWM, used as a laser spectroscopy for gas phase trace detection,is receiving a great deal of attention in combustion diagnostics. In this technique three laser beams, tuned at the same wavelength, interfere in a gaseous medium containing a resonant species. Two laser beams, interacting with the (chi) 3 of the medium, generate a grating which is read by the third laser and scatters the signal beam at the same wavelength. The NO molecule and OH radical have been detected in small undoped flames by performing space resolved concentration and temperature measurements in forward BOXCARS geometry. The NO space distribution has been investigated in a C2H2/air flame by exciting the (gamma) transition around 226 nm. Flame temperature and NO concentration have been calculated after calibration on room temperature cell data. The OH DFWM spectrum of the A2(Sigma) +-X2(Pi) vibrationally excited transition peaked around 284 nm has ben recorded in C2H2/air and isobuthane/air flames, corresponding flame temperatures have been determined. The possibility of NO2 detection in flame outlets has been investigated by studying the effects of collisional energy redistribution on its Douglas-Huber band DFWM spectrum measured in air mixtures at different pressures and temperatures.
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Roberta Fantoni, Luigi De Dominicis, Mariano Giorgi, "Combustion diagnostic using degenerate four wave mixing spectroscopy", Proc. SPIE 3108, Combustion Diagnostics, (23 May 1997); doi: 10.1117/12.274762; https://doi.org/10.1117/12.274762
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KEYWORDS
Temperature metrology

Combustion

NOx

Spectroscopy

Molecules

Four wave mixing

Laser beam diagnostics

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