Choo, Chin Heng (1996) Brillouin scattering from a gas subject to a temperature gradient : optical considerations. Masters thesis, Memorial University of Newfoundland.
PDF (Migrated (PDF/A Conversion) from original format: (application/pdf))
- Accepted Version
Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
This thesis describes an attempt to use the Brillouin light scattering technique to observe nonequilibrium effects in gaseous sulphur hexafluoride subject to a temperature gradient. Due to the inherent geometry of the experimental setup, an imaging fibre optic probe was investigated as a means of scattered light collection. The SF₆ gas was housed in a moderate pressure gas cell. The scattered light collected was analyzed with a Fabry-Perot interferometer. A computer simulation of the behaviour of temperature, density and refractive index for gaseous SF₆ subject to a temperature gradient was performed using a 2 dimensional nonconvective heat flow model. A computer simulation of the scattered ray paths from the gas cell to the optical fibre in the imaging fibre optic probe was also performed. The sound speed in SF₆ at a pressure of 1.28 MPa and a temperature of 20°C was measured to be 133 ± 6 m.s⁻¹. Sound speeds in SF₆ for pressures from 0.44 MPa to 1.83 MPa were also measured. These sound speeds showed a larger nonlinearity in its changed with different pressures than that calculated from theory. Nonequilibrium Brillouin spectra for SF₆ were observed at pressures of 0.891 MPa and 1.35 MPa with temperature gradients of about 15.3 K cm⁻¹ and 18.9 K cm⁻¹, respectively. The Brillouin components at nonequilibrium showed an intensity increase of about 16% when compared to their counterparts at equilibrium.
|Item Type:||Thesis (Masters)|
|Additional Information:||Bibliography: leaves 71-73.|
|Department(s):||Science, Faculty of > Physics and Physical Oceanography|
|Library of Congress Subject Heading:||Brillouin scattering; Nonequilibrium thermodynamics; Sulphur hexafluoride--Optical properties|
Actions (login required)