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Proceedings Paper

Modeling of spacecraft contamination outgassing as a diffusion-controlled process
Author(s): David M. Silver
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Paper Abstract

The 3D diffusion equation is solved for molecular outgassing from a porous layer of sample material covering an inert substrate in the form of a right circular cylinder. Expressions are derived for the time dependence of the residual concentrations of outgassable materials in the porous layer and the masses of outgassable materials that are leaving the porous layer. A separate diffusion function can be extracted from outgassing measurement data for each grouping of outgassing molecules corresponding to the mass deposited on temperature-controlled quartz crystal microbalances held at different temperatures. The different time dependences of the different diffusing species are described by individual diffusion coefficients. The analytic form of the diffusion function permits extrapolation of residual concentrations of outgassing molecules to long times for each grouping of molecular components.

Paper Details

Date Published: 18 December 1992
PDF: 9 pages
Proc. SPIE 1754, Optical System Contamination: Effects, Measurement, Control III, (18 December 1992); doi: 10.1117/12.140750
Show Author Affiliations
David M. Silver, Johns Hopkins Univ. (United States)


Published in SPIE Proceedings Vol. 1754:
Optical System Contamination: Effects, Measurement, Control III
A. Peter M. Glassford, Editor(s)

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