Determination of radiative properties in a radially symmetric plasma colum from remote spectral scanning by spectroscopy and photodetection

Abstract

An algorithm was developed to calculate radiative transfer properties and temperature of a laser produced plasma from remote spectrometer and photodetection measurements. The plasma is assumed to be radially symmetric and to have been formed from a pulsed Nd:Glass laser striking an aluminum sample. The temperature and the properties are calculated for all radial positions at a single height and time. The specific properties obtained are for a wavelength of 632.8 nm and include the volumetric emission coefficient, absorption coefficient, scattering coefficient, extinction coefficient, scattering albedo, and phase angle function. Knowledge of the temperature and radiative properties of a laser produced plasma enable a better understanding of the role of the plasma in energy transfer to the surface. The plasma can serve as either a shield or an enhancement to the laser irradiation, where the physical basis is not well known. Computer programs have been developed to extract the required data from spectrometer and photodetection measurements. Data from the literature was used to test the model. The model predicts shielding of the laser near the plasma center with high absorption and emission coefficients. Results indicate that there is a strong radial dependency for all radiative properties including the scattering albedo. Scattering coefficients change less than other radiative properties as a function of radius. Near the edge of the plasma the radiative properties indicate that it is optically thin. Comparisons were made to reported experimental and other modeling studies.

Notes

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Graduation Date

1991

Semester

Fall

Advisor

Bishop, Patricia

Degree

Master of Science (M.S.)

College

College of Engineering

Department

Mechanical and Aerospace Engineering

Format

PDF

Pages

350 p.

Language

English

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Identifier

DP0027985

Subjects

Dissertations, Academic -- Engineering; Engineering -- Dissertations, Academic

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