Speaker
Dmitry Terentyev
(SCK-CEN)
Description
Recent theoretical and subsequent experimental studies suggest that the uptake and release of deuterium (D) in tungsten (W) under high flux plasma exposure (i.e. under ITER-relevant conditions) is controlled by dislocation microstructure induced by the plasma itself. A comprehensive mechanism for the nucleation and growth of D bubbles on dislocation network under high flux low-energy plasma exposure was proposed and validated. The process of bubble nucleation can be described as D atom trapping at a dislocation line, its in-core migration, the coalescence of several D atoms into a multiple cluster, which eventually transforms into a nano-bubble by punching out matrix atoms on the dislocation line. This view implies that the initial microstructure might be crucial for D uptake and degradation of the sub-surface layer under prolonged plasma exposure. Understanding of the role played by the initial microstructure is the purpose of this work.
In this work, we apply several experimental techniques to investigate the microstructure and mechanical properties of surface and sub-surface layer of W exposed to the high flux plasme. In particular, we use transmission and scanning electron microscopy, as well as nano-indentation measurements. To reveal the impact of the initial microstructure, we have performed exposures in single crystal, poly-crystal and heavily deformed polycrystal tungsten samples. The preliminary TEM study demonstrates that even in single crystal sample, high flux plasma exposure induces high density of dislocations and tanges in the sub-surface area. The presence of the plasma-induced microstructure is well detected by the nano-indentation experiments, which provide reach information about change of material hardness and depth distribution of the irradiation-induced microstructure.
Co-authors
Anastasia Bakaeva
(SCK-CEN, Mol, Belgium)
Andrii Dubinko
(SCK-CEN, Mol, Belgium;SCK-CEN, Mol, Belgium)
Dmitry Terentyev
(SCK-CEN, Mol, Belgium)
