Characterization of hydrogen binding to tungsten and beryllium surfaces using low energy ion beam analysis

In this study, we use low energy ion beam analysis to determine how hydrogen interacts with tungsten and beryllium surfaces. The goal of this work is to provide insight into processes that contribute to recycling from plasma-facing surfaces in magnetic fusion devices. Here we have applied low energy ion scattering (LEIS) to enable detection of adsorbed hydrogen at sub-monolayer resolution and to provide isotopic sensitivity. We probe the surfaces of interest with He$+$ and Ne$+$ at energies less than 5 keV to determine the structure and composition of the first few atomic layers. This approach enables us to examine how hydrogen surface concentrations evolve in real time, providing insight into adsorption kinetics. In addition, we have developed a means of determining the hydrogen binding configuration at different temperatures by exploiting mechanisms of ion channeling along surfaces. Using these methods, we have been able to identify hydrogen binding configurations for the W(100)$+$H, W(110)$+$H, and Be(0001)$+$H adsorption systems. We also report on our efforts to more accurately and efficiently model atomic collisions during scattering, key steps needed to extract structural information from LEIS signals.