In-situ analysis of titanium-deuterium plasma-material interactions relevant to fusion applications

Wall coatings such as titanium are critical to improving performance by controlling recycling through hydrogen absorption and reducing impurity concentrations in next-generation fusion reactors. Here, we carry out a fundamental study of titanium-deuterium plasma-material interactions using low-energy (1 keV) deuterium ions and in-situ thermal desorption spectroscopy and X-ray photoelectron spectroscopy, complemented by ex-situ scanning electron microscopy. We observe that deuterium desorption strongly depends on ion fluence, surface temperature, and target thickness. Deuterium uptake is dominated by ion implantation up to ∼500 K, above which molecular (i.e., neutral) absorption dominates. Microstructure analysis and depth profiling reveal a deuterium-rich surface layer; however, no saturation is observed in the absorption, suggesting surface-driven effects such as ion bombardment or diffusion. These findings provide important insight for the development of advanced models to more accurately describe plasma-material interactions with reactive metals in the low-energy regime.