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.
Low-energy proton implantation of stainless steel
Hydrogen gas re-emission and scanning electron microscopy measurements were conducted on a series of cold-worked Types 316 and 302 stainless-steel specimens implanted with 20-keV protons at tempera...
Photoreflectance characterization of vanadium-doped GaAs layers grown by metalorganic vapor phase epitaxy
Abstract We characterized the vanadium-doped (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy. The conductivity of the samples is checked by the Hall effect measurements, and it is n type with electrons concentration ranging from 2×10 13 to 2×10 17  cm −3 . We used the photoreflectance technique (PR) to study the effect of vanadium doping on the optical properties of GaAs. Our experimental results show that the built-in electric field F and the broadening parameter Γ 0 increase with V-doping concentration. Furthermore, the temperature dependence of the built-in electric field and the broadening parameter of GaAs:V samples have been investigated by PR. It has been observed that these parameters increase with increasing temperature. The decrease of the built-in electric field with decreasing temperature is due to the photovoltage effect.We characterized the vanadium-doped GaAs (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy.