The New Jersey Institute of Technology's
Electronic Theses & Dissertations Project

Title:	Measurement of gas flow through porous structures using thz spectroscopy
Author:	Wang, Yihui
View Online:	njit-etd2013-037 (ix, 25 pages ~ 0.8 MB pdf)
Department:	Committee for the Interdisciplinary Program in Materials Science and Engineering
Degree:	Master of Science
Program:	Materials Science and Engineering
Document Type:	Thesis
Advisory Committee:	Federici, John Francis (Committee chair) Ravindra, N. M. (Committee member) Barat, Robert Benedict (Committee member)
Date:	2013-05
Keywords:	Gas flow Porous material Terahertz spectroscopy
Availability:	Unrestricted
Abstract:	Comparing THz transmission through a sample with the transmission through free-space allows one to calculate the THz absorbance of a sample. Previous studies have focused on using THz absorbance to measure the diffusion of liquid through materials. In this study, the ability of THz spectroscopy to measure the flow of gas in a porous material, packaging foam, is investigated. Specifically, Terahertz spectroscopy from 0.5 to 0.7 THz is used to measure the THz absorption of 1, 1 -difluoroethane. Several experiments are performed to test the ability of THz spectroscopy to measure the flow of gas in a porous material: (1) The gas cell is empty (no foam) during the filling and purging of the gas cell. (2) Two layers of foam are put in the gas cell. The gas outlet at the bottom of the gas cell is left open. (3) Two layers of foam are placed in the gas cell. In this condition, the gas outlet at the bottom of the cell is left only partially open. The data shows that THz spectroscopy can be used to measure the flow of gas in opaque porous materials. The longer term goal of thesis research is to eventually use the THz properties of the gas to measure its diffusion through different porous products and correlate the gas diffusion with the material’s structure.