Physical contamination results from a competition between the deposition of incoming contaminants and their reemission, depending on the surface temperature. However, interaction with ultraviolet light greatly inhibits reemission. Ultraviolet light can lead to chemical reactions, bonding contaminants to the substrate or nearby molecules. This effect can have important consequences in flight. This is especially true for hot surfaces that show no contamination in the absence of ultraviolet light due to their high temperature and can nevertheless be significantly contaminated through photofixation. Previous studies conducted by ONERA–The French Aerospace Lab with Centre National d’Etudes Spatiales allowed identifying the physical mechanisms involved in photofixation and led to a sufficiently simple model to be implemented in engineering software. In this model, the substrate excitation is followed by the reaction of adsorbed contaminants with excited sites. Contaminant chemical photofixation thus results from the competition between their reemission and their reaction with excited sites. This paper presents the implementation of this photofixation model in the numerical tool COMOVA and its validation. It was carried out by modeling test cases, including ground experiments. It demonstrated the qualitative coherence of the photofixation model. The simplest experimental cases with pure contaminants, which have analytical solutions, also quantitatively validated the physical model and its numerical implementation.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Ultraviolet Fixation of Molecular Contamination: Physical Model Numerical Implementation and Validation


    Contributors:

    Published in:

    Publication date :

    2016-07-27


    Size :

    7 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English







    Experiments and Physical Modeling of Ultraviolet-Enhanced Contamination from Pure Contaminants

    Alexandre Pereira / Jean-François Roussel / Marc Van Eesbeek et al. | AIAA | 2006


    New Mechanism for VUV Fixation of Contamination

    Tondu, T. / Roussel, J.-F. / Faye, D. et al. | British Library Conference Proceedings | 2013