Analyse de surface d'échantillons exposés à des décharges luminescentes dans le Tokamak de Varennes

Abstract

The effects of surface conditioning discharges were studied at the Varennes tokamak. Pre-analyzed samples were exposed to glow discharges in helium or hydrogen and then reanalyzed. Exposures to discharges took place in the vacuum chamber of the tokamak, and the analyses were carried out at INRS-Energie, by Auger electron spectroscopy with ionic etching (depth profile). Samples were transferred in vacuum. Chemical effects of hydrogen discharges and physical erosion effects of helium discharges were observed. We also observed that hydrogen and helium discharges produced graphite carbon (carbonization) or metallic carbide (carburization). These observations show the importance of the modifications of the discharge owing to its interaction with the wall and the graphite limiting devices in the Varennes tokamak.[Journal translation]