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Uncertainty and sensitivity analysis in complex plasma chemistry models

Turner, Miles M. (2016) Uncertainty and sensitivity analysis in complex plasma chemistry models. Plasmas Source Science and Technology, 25 (1). 015003-015003. ISSN 1361-6595

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Abstract

The purpose of a plasma chemistry model is prediction of chemical species densities, including understanding the mechanisms by which such species are formed. These aims are compromised by an uncertain knowledge of the rate constants included in the model, which directly causes uncertainty in the model predictions. We recently showed that this predictive uncertainty can be large—a factor of ten or more in some cases. There is probably no context in which a plasma chemistry model might be used where the existence of uncertainty on this scale could not be a matter of concern. A question that at once follows is: which rate constants cause such uncertainty? In the present paper we show how this question can be answered by applying a systematic screening procedure—the so-called Morris method—to identify sensitive rate constants. We investigate the topical example of the helium–oxygen chemistry. Beginning with a model with almost four hundred reactions, and focussing on conditions relevant to biomedical applications, we show that only about fifty rate constants materially affect the model results, and as few as ten cause most of the uncertainty. This means that the model can be improved, and the uncertainty substantially reduced, by focussing attention on this tractably small set of critical rate constants. We discuss strategies that might be used to accomplish this refinement. The present results apply to a particular chemistry, but we suggest that possibly, and perhaps probably, investigations of other plasma chemistry models will arrive at similar results. In that case, an opportunity exists to systematically improve the quality of plasma chemistry modelling.

Item Type:Article (Published)
Refereed:Yes
Subjects:Physical Sciences > Plasmas
Physical Sciences > Plasma processing
Physical Sciences > Chemistry
Computer Science > Computer simulation
DCU Faculties and Centres:Research Initiatives and Centres > National Centre for Plasma Science and Technology (NCPST)
DCU Faculties and Schools > Faculty of Science and Health > School of Physical Sciences
Publisher:Institute of Physics
Official URL:http://dx.doi.org/10.1088/0963-0252/25/1/015003
Copyright Information:© 2016 IOP
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 License. View License
Funders:Science Foundation Ireland 08/SRC/I1411, COST Action MP1101 'Biomedical Applications of Atmospheric Pressure Plasmas'
ID Code:20935
Deposited On:02 Dec 2015 12:06 by Miles Turner. Last Modified 02 Dec 2015 12:06

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