Hannover 2020 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 16: Poster Session 3
P 16.11: Poster
Mittwoch, 11. März 2020, 16:30–18:30, Empore Lichthof
Effects of oxide layers on deuterium uptake, retention and release in self-damaged tungsten — •Kristof Kremer1,2, Maximilian Brucker1,3, and Thomas Schwarz-Selinger1 — 1MPI for Plasma Physics, Boltzmanstraße 2, D-85748 Garching, Germany — 2TUM, James-Franck-Straße 1, D-85748 Garching, Germany — 3Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
Understanding hydrogen isotope (HI) retention in first-wall materials is crucial to predict fuel loss in future fusion devices, but the influence of surface oxides is discussed controversially in literature.
We examine the effect of thick (25–100 nm) tungsten-oxide layers on uptake, retention and release of HI in tungsten (W) by oxidizing the sample and then exposing it to a deuterium (D) plasma at low ion energy (< 5eV/D) and low temperature (370 K) to minimized erosion of the oxide. As samples, self-damaged W is used. Damaging with 20 MeV W ions creates a ∼ 2 µm thick, defect-rich getter layer that retains HIs. Nuclear reaction analysis, Rutherford back scattering and Thermal Desorption Spectroscopy (TDS) are used to quantify the amount of oxygen, the depth profiles of the retained D and the outgassing behavior. A strong influence of surface oxide layers on D uptake is observed, i.e., oxide layers strongly suppress D uptake. The oxide layer itself is only partially reduced by plasma exposure and only partially evaporated during TDS up to 1000 K. The role of thin (∼ 2 nm), natural oxide layers are subject of future investigations. In this regard, we are setting up an in-situ experiment to examine HI uptake, retention and release on oxide-free W surfaces.