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Proceedings Paper

Modeling of transmittance degradation caused by optical surface contamination by atomic oxygen reaction with adsorbed silicones
Author(s): Aaron Snyder; Bruce A. Banks; Sharon K. Miller; Thomas Stueber; Edward Sechkar
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Paper Abstract

A numerical procedure is presented to calculate transmittance degradation caused by contaminant films on spacecraft surfaces produced through the interaction of orbital atomic oxygen (AO) with volatile silicones and hydrocarbons from spacecraft components. In the model, contaminant accretion is dependent on the adsorption of species, depletion reactions due to gas-surface collisions, desorption, and surface reactions between AO and silicon producing SiOx (where x is near 2). A detailed description of the procedure used to calculate the constituents of the contaminant layer is presented, including the equations that govern the evolution of fractional coverage by specie type. As an illustrative example of film growth, calculation results using a prototype code that calculates the evolution of surface coverage by specie type is presented and discussed. An example of the transmittance degradation caused by surface interaction of AO with deposited contaminant is presented for the case of exponentially decaying contaminant flux. These examples are performed using hypothetical values for the process parameters.

Paper Details

Date Published: 20 September 2000
PDF: 12 pages
Proc. SPIE 4096, Optical Systems Contamination and Degradation II: Effects, Measurements, and Control, (20 September 2000); doi: 10.1117/12.400826
Show Author Affiliations
Aaron Snyder, NASA Glenn Research Ctr. (United States)
Bruce A. Banks, NASA Glenn Research Ctr. (United States)
Sharon K. Miller, NASA Glenn Research Ctr. (United States)
Thomas Stueber, Dynacs Engineering Co., Inc. (United States)
Edward Sechkar, Dynacs Engineering Co., Inc. (United States)

Published in SPIE Proceedings Vol. 4096:
Optical Systems Contamination and Degradation II: Effects, Measurements, and Control
Philip T. C. Chen; O. Manuel Uy, Editor(s)

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