Hydrogen Trapping Studies in Fusion First Wall Materials
Hydrogen trapping in the first wall of fusion reactors is one of the most serious materials problems facing the designers of magnetic confinement devices. The release of this trapped hydrogen from the near surface region of the first wall during a tokamak discharge has been shown to play a major role in the hydrogen fueling of today's plasmas, while trapped hydrogen isotopes will directly influence the on-site tritium inventory and the structural properties of future D-T reactors. This paper summarizes the laboratory ion implantation sttidies on the hydrogen trapping characteristics of first wall materials. Emphasis is placed on the near term materials problems associated with austenitic stainless steels that are currently in use in magnetic confinement devices. Hydrogen trapping experiments involving more exotic first wall structural and coating materials are briefly reviewed.
Deuteron trapping in titanium
Abstract A tensimetric technique has been developed for measuring 15 keV D + trapping in Ti metal. The formation of the TiD 2 phase in the surface and near-surface regions was monitored by decoupling the θ–2θ scan of an X-ray diffractometer as well as by scanning electron microscope studies. Micron-sized ‘reaction zones’ appear to serve as nucleation centers for the TiD 2 phase. Insight into the mechanism of chemical trapping is obtained by correlating the results from the three types of measurements used in the present work.
Desorption of adsorbed and condensed gases on metals by deuterons
Abstract Metal surfaces have been bombarded with deuterons in the energy range 5–35 keV and mass spectra of the gases desorbed observed. The principal gases released are hydrogen and carbon monoxide. Layers of carbon dioxide and water vapour were then bombarded and shown to dissociate. Two methods of measuring the yield of gas released from these layers are described and the results compared.