Contamination of Ultrapure Systems by Back-Diffusion of Gaseous Impurities

Nishith K. Verma; Asad M. Haidel; Farhang Shadman

doi:10.1149/1.2221579

Contamination of Ultrapure Systems by Back-Diffusion of Gaseous Impurities

Nishith K. Verma, Asad M. Haidel, Farhang Shadman

Research output: Contribution to journal › Article › peer-review

13 Scopus citations

Abstract

Diffusion of impurities against the direction of gas flow can be a significant source of contamination in the ultrapure gas systems. The mechanism and the kinetics of impurity transport due to back-diffusion is studied both experimentally and theoretically. A model is developed to simulate the process and calculate the extent of impurity transport due to back-diffusion. Experiments for measuring oxygen back-diffusion in a nitrogen carrier stream are conducted. The data and the model predictions are in good agreement. Back-diffusion involves both bulk and surface diffusion and is higher for lower pressures, lower flow rates, larger tube diameters, and for smaller nonadsorbing molecules.

Original language	English (US)
Pages (from-to)	1459-1463
Number of pages	5
Journal	Journal of the Electrochemical Society
Volume	140
Issue number	5
DOIs	https://doi.org/10.1149/1.2221579
State	Published - May 1993

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Renewable Energy, Sustainability and the Environment
Surfaces, Coatings and Films
Electrochemistry
Materials Chemistry

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abstract = "Diffusion of impurities against the direction of gas flow can be a significant source of contamination in the ultrapure gas systems. The mechanism and the kinetics of impurity transport due to back-diffusion is studied both experimentally and theoretically. A model is developed to simulate the process and calculate the extent of impurity transport due to back-diffusion. Experiments for measuring oxygen back-diffusion in a nitrogen carrier stream are conducted. The data and the model predictions are in good agreement. Back-diffusion involves both bulk and surface diffusion and is higher for lower pressures, lower flow rates, larger tube diameters, and for smaller nonadsorbing molecules.",

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AB - Diffusion of impurities against the direction of gas flow can be a significant source of contamination in the ultrapure gas systems. The mechanism and the kinetics of impurity transport due to back-diffusion is studied both experimentally and theoretically. A model is developed to simulate the process and calculate the extent of impurity transport due to back-diffusion. Experiments for measuring oxygen back-diffusion in a nitrogen carrier stream are conducted. The data and the model predictions are in good agreement. Back-diffusion involves both bulk and surface diffusion and is higher for lower pressures, lower flow rates, larger tube diameters, and for smaller nonadsorbing molecules.

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Contamination of Ultrapure Systems by Back-Diffusion of Gaseous Impurities

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