ETUDE DU COMPORTEMENT THERMIQUE D'UN MATERIAU MULTICOUCHES LACUNAIRES ET CONTRIBUTION A LA MODELISATION ET LA SIMULATION NUMERIQUE DES DEPOTS A STRUCTURE COLONNAIRE.

Abstract : The work presented in this thesis is justified by both technological and economic problems related to the improvent of the cathodic ray tube screen. More precisely, it concerns one of its part called mask which is a grid in front of the screen. ITS role is to select precisely a
photophore excited by the electronic beam : in fact most of the energy of the beam is deposed on the mask (80%, for 20% for the photophores) which temperature increases. Consequently, it
experiences a bending which damages the image quality. The solution which has been studied here consists in the deposit of thin layers of material chosen for their thermical and mechanical properties. This thesis include two parts :

- The first one is devoted to a thermic study, that is the heating of the mask due to the scanning of the electronic beam and to verify if the solution proposed here reduces the thermic gradients. First, using a homogenisation technic, we proposed a model without layers which
take into account the holes of the mask. Then, we study the role of different layers on the radial propagation of the energy.

- The second one is devoted to the modelisation and numerical simulations of the deposition process of thin layers on the mask. It includes two types of approaches : one is based on discrete
models which are simulated by Monte Carlo methods ; the other involves stochastic partial differential equations. The prerequisite of the models is that their solutions are able to recover the columnar shape deposit observed in plasma technic operationally used. Then we focused our study on models which take into account the shadowing which is a good candidate and indeed produces such structures experimentally oberserved. The study of the influence of the different terms (relaxation, shadowing,...) on both models (MC and PDE) allow us to proposed a new continuous model, the solutions of which are of columnar type, similar to those produced
by discrete models including shadowing. This study has been done in 1+1D and 2+1D.
Document type :
Theses
Mathematics. Université d'Orléans, 2007. French
Domain :


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Submitted on : Saturday, November 22, 2008 - 11:33:17 PM
Last modification on : Monday, November 24, 2008 - 10:31:38 AM

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Thu Huong Vo Thi. ETUDE DU COMPORTEMENT THERMIQUE D'UN MATERIAU MULTICOUCHES LACUNAIRES ET CONTRIBUTION A LA MODELISATION ET LA SIMULATION NUMERIQUE DES DEPOTS A STRUCTURE COLONNAIRE.. Mathematics. Université d'Orléans, 2007. French. <tel-00340855>

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