Study of the chemical sputtering in Tore Supra
The work presented in this thesis focuses on the interaction between energetic particles coming from thermonuclear plasma and the inner components of a fusion machine. This interaction includes two major problems: erosion of the wall and tritium retention. This report deals with the erosion of carbon-based materials. The first pat is devoted to chemical sputtering, which appears to be the principal erosion mechanism, compared to physical sputtering and radiation enhanced sublimation that can both be limited. Chemical sputtering has been studied in situ in the tokamak Tore-Supra for ohmic and lower hybrid (LH) heated discharges, by means of mass spectrometry and optical spectroscopy. We have shown that it is necessary to take into account both methane and heavier hydrocarbons (C(2)D(x) and C(3)D(y)) in the determination of the chemical sputtering yield. The experimental study also reveals that an increase of the surface temperature induces an augmentation of Y(CD4). In the second part of this work, we have developed and installed an infrared spectroscopy diagnostic in the 0.8 - 1.6µm wavelength range dedicated to the measurement of surface temperature, and the identification of atomic and molecular lines emitted during plasma/wall interactions. In the third part, we present the feasibility study of an in situ tungsten deposition process at low temperature (<80°C) in order to suppress the chemical sputtering. This study shows that, with this method called Plasma Assisted Chemical Vapour Deposition (PACVD), we are able to coat the whole inner vessel of a tokamak with 1µm of tungsten.
Bibliographic Reference: CEA Cadarache, Report no. EUR-CEA-FC-1728, November 2002. pp.210.
Availability: Available from Association EURATOM-CEA, Département de Recherches sur la Fusion Contrôlée, CEA Cadarache, F-13108 St Paul-Lez-Durance, France Tel: (+33) 4 42 25 70 01; Fax: (+33) 4 42 25 64 21 E-mail: email@example.com
Record Number: 200215658 / Last updated on: 2002-12-13
Original language: fr
Available languages: fr