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Proceedings Paper

Investigation of molecular angular distribution and its influence on contaminant transmission
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Paper Abstract

The fraction of neutral molecules transmitted through a restrictive passage in molecular flow can be highly dependent on the shape of the reservoir from which the gas originates. A particular reservoir shape was investigated to determine its effect on the angular distribution of molecules entering two types of simple restrictive passages. It was determined that a reservoir consisting largely of two-dimensional shells imparted a bimodal distribution to the reservoir gas, resulting in lemniscate flux distributions for the gas entering a baffle network. A Monte Carlo code was developed and compared to analytical transmission probabilities calculated by Clausing. After establishing the validity of the code, the effects of lemniscate and Lambertian flux distributions for molecular flow were simulated for two-dimensional channels and right- angle bends for various length-to-height ratios. It was determined that the shape of the entrance distribution can play an important role in the calculation of transmission probabilities.

Paper Details

Date Published: 11 November 1996
PDF: 12 pages
Proc. SPIE 2864, Optical System Contamination V, and Stray Light and System Optimization, (11 November 1996); doi: 10.1117/12.258299
Show Author Affiliations
Michael S. Woronowicz, Swales and Associates, Inc. (United States)
Philip T. C. Chen, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 2864:
Optical System Contamination V, and Stray Light and System Optimization
Robert P. Breault; A. Peter M. Glassford; Stephen M. Pompea; Robert P. Breault; Stephen M. Pompea, Editor(s)

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