Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Singh, Jagdish P.

Committee Member

Monts, David L.

Committee Member

Su, Chun Fu

Committee Member

Yueh, Fang Yu

Committee Member

Norton, Olin Perry

Other Advisors or Committee Members

Philip, Thomas

Date of Degree

1-1-2009

Document Type

Dissertation - Open Access

Degree Name

Doctor of Philosophy

College

College of Arts and Sciences

Department

Department of Physics and Astronomy

Abstract

In this doctoral dissertation, two laser-based sensors were evaluated for different applications. Laser Induced Incandescence (LII) is a technique which can provide nonintrusive quantitative measurement of soot and it provides a unique diagnostic tool to characterize engine performance. Since LII is linearly proportional to the soot volume fraction, it can provide in situ, real time measurement of soot volume fraction with high temporal and spatial resolution. LII has the capability to characterize soot formation during combustion. The soot volume fraction from both flames and a soot generator was investigated with LII. The effects of experimental parameters, such as laser fluence, gate delay, gate width and various laser beam focusing, on LII signal was studied. Laser Induced Breakdown Spectroscopy (LIBS), a diagnostic tool for in situ elemental analysis, has been evaluated for on-line, simultaneous, multi-species impurity monitoring in hydrogen. LIBS spectra with different impurity levels of nitrogen, argon, and oxygen were recorded and the intensity of the spectral lines of Ar, O, N, and H observed were used to form calibration plots for impurities in hydrogen measurements. An ungated detection method for LIBS has been developed and applied to equivalence ratio measurements of CH4/air and biofuel/air. LIBS has also been used to quantitatively analyze the composition of a slurry sample. The quenching effect of water in slurry samples causes low LIBS signal quality with poor sensitivity. Univariate and multivariate calibration was performed on LIBS spectra of dried slurry samples for elemental analysis of Mg, Si and Fe. Calibration results show that the dried slurry samples give good correlation between spectral intensity and elemental concentration.

URI

https://hdl.handle.net/11668/20767

Comments

LII||hydrogen gas||spectormeters||spectroscopy||LIBS||slurry||limit of detection||multivariate analysis

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