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Progress in Plasma Processing of Materials, 2003

ISBN:
978-1-56700-192-1 (Print)
978-1-56700-447-2 (Online)

MECHANISMS AND MODELLING OF THE HEAT AND OF MASS TRANSFER DURING ATOMIC OXYGEN RECOMBINATION ON METALLIC SEMICONDUCTORS IN A PLASMA REACTOR.

C. Guyon
Laboratoire de Génie des Procédés Plasmas et Traitement de Surfaces, Universite Pierre & Marie Curie, 11 rue Pierre et Marie Curie, 75231 Paris Cedex, France

N. Rouckout
Laboratoire de Genie des Precedes Plasma et Traitement de Surface Universite Pierre & Marie Curie - ENSCP - 11, rue P. & M. Curie 75231 Paris Cedex 05 (France)

S. Cavadias
Laboratoire Genie Precedes Plasmas - ENSCP 11, rue Pierre et Marie Curie - 75005 Paris- France

Jacques Amouroux
Laboratoire de Genie des Precedes Plasmas Universite P. et M. Curie, ENSCP 11 rue P. et M. Curie 75005 Paris France

Abstract

Space shuttle overheating during the re-entry phase, due to catalytic oxygen recombination on the thermal protection system, is a problem of practical and theoretical interest. The energy transfer is characterised by the product of the accommodation and the recombination coefficients (respectively γ and β coefficients). Previous measurements of recombination coefficient "gamma" on the metallic samples allowed the establishment of a catalycity scale. The experimental study is undertaken on semiconductors and on ceramics materials which presents interesting properties as refractory material. In the first part of this work the measurements are performed on a large temperature range (300 - 923 K) in order to evaluate the catalycity as a function of temperature. In the second purpose of this work is presented the modelling of the recombination of oxygen atoms and transfer of the energy to a metallic or ceramic material by using the Chemkin® code. The flow is described by a system of equations (conservation of species and energy). The necessary boundary conditions were provided by a model for a reactive flow-surface interaction. Under conditions similar to the experiment the field velocity, temperature and the fluxes of atomic and molecular oxygen in the reactor have been obtained. The results shows a good agreement for at least silica.