Investigation of Degenerate Four -Wave Mixing and Polarization Spectroscopy for Quantitative Measurements in Combustion Environments

The application of DFWM and PS for quantitative concentration measurements was investigated experimentally by measuring lineshapes and signal intensities in well-characterized hydrogen/air flames. Resonances in the A2Sigma +-X2pi (0,0) band of hydroxyl (OH) were probed with both perturbative and saturating beam intensities. Hydroxyl number densities were calculated from the DFWM and PS signal intensities in a series of near-adiabatic flames at equivalence ratios ranging from 0.5 to 1.5. The use of saturating laser intensities minimized the effects of beam absorption and variation of the collisional dynamics, providing more accurate number density measurements. The saturated DFWM results and the saturated PS results were in excellent agreement with OH absorption measurements and equilibrium calculations of OH concentration. The polarization dependence of the P1(2) and R2(l) DFWM transitions was investigated, providing experimental confirmation that the signal penalties predicted by a perturbative treatment of DFWM can be much less when the resonances are saturated.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Reichardt, Thomas Andrew

Contributors dc:contributor

• Lucht, Robert P.

• Physics, Optics

Language dc:language

eng

Identifier

(MiAaPQ)AAI9944981

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/83985