SMuK 2021 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 5: Poster I
P 5.21: Poster
Dienstag, 31. August 2021, 14:00–16:00, P
Effects of thin surface oxide films on deuterium uptake in self-damaged tungsten - Evidence for permeation barrier effect — •Kristof Kremer1,2, Thomas Schwarz-Selinger1, and Wolfgang Jacob1 — 1Max-Planck-Institut für Plasmaphysik, 85748 Garching, Deutschland — 2Physik-Department E28, Technische Universität München, 85747 Garching, Germany
In a fusion reactor, the uptake of deuterium (D) and tritium fuel into the plasma-facing tungsten (W) components is a critical issue with respect to fuel loss and radioactive inventory. However, the possible influence of natural surface oxides on the D uptake in W is not fully understood yet.
Therefore, we investigated the D uptake in W through 33 and 55 nm thick oxide films. To trace the D, a 2 µm thick layer of self-ion-damaged W was created underneath the oxide. It acts as a getter layer and traps any D that permeates the oxide film. The sample was then exposed to a "gentle" D plasma (<5eV/D ion) at 370 K to a fluence of 1024 D/m2. We measured the depth-resolved concentration of D and oxygen with nuclear reaction analysis and Rutherford backscattering spectroscopy and the surface modifications of the oxide film with scanning electron microscopy.
We observed a strong influence of surface oxide films on D uptake, i.e., the oxide films completely block D uptake into metallic W, although high D concentrations were found in the oxide film itself. We explain this by the difference in the heat of solution between W oxide and metallic W.