Method of conservatively predicting long-term outgassing and deposition levels based on diffusion-limited outgassing theory

Timothy J. Girard; Richard M. Payton

doi:10.1117/12.190136

19 October 1994 Method of conservatively predicting long-term outgassing and deposition levels based on diffusion-limited outgassing theory

Timothy J. Girard, Richard M. Payton

Author Affiliations +

Proceedings Volume 2261, Optical System Contamination: Effects, Measurements, and Control IV; (1994) https://doi.org/10.1117/12.190136
Event: SPIE's 1994 International Symposium on Optics, Imaging, and Instrumentation, 1994, San Diego, CA, United States

Abstract

A method is presented that conservatively predicts long term outgassing for materials outgassing diffusely using short term test data. Accurate long term predictions require knowledge of the diffusion coefficient and initial concentrations of each species outgassed from a material which are obtainable only from often prohibitively long term testing. The method presented demonstrates how one can utilize standard 24 hour TML/CVCM data or short term outgassing rate testing data to conservatively predict long term outgassing. The method is based upon diffusion theory which predicts that the amount of material outgassing is proportional to the product of a constant, the square root of time, and a function that decays with time with maximum value of 1. The conservative approach taken is to assume that outgassing is proportional to a constant times the square root of time, replacing the decaying function with its maximum value of 1.

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Timothy J. Girard and Richard M. Payton "Method of conservatively predicting long-term outgassing and deposition levels based on diffusion-limited outgassing theory", Proc. SPIE 2261, Optical System Contamination: Effects, Measurements, and Control IV, (19 October 1994); https://doi.org/10.1117/12.190136

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