Erlangen 2018 – scientific programme

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P: Fachverband Plasmaphysik

P 15: Helmholtz Graduate School IV - Plasma Wall Interaction

P 15.3: Talk

Wednesday, March 7, 2018, 14:50–15:15, A 0.112

The influence of dislocations, vacancies, and vacancy clusters on deuterium trapping in tungsten — •Mikhail Zibrov¹, Matej Mayer¹, Armin Manhard¹, Dmitry Terentyev², Andrii Dubinko², and Werner Egger³ — ¹Max-Planck-Institut für Plasmaphysik, Garching, Germany — ²SCK-CEN, Mol, Belgium — ³Universität der Bundeswehr München, Neubiberg, Germany

The hydrogen (H) isotope inventory in tungsten (W) is governed by the presence of lattice defects acting as trapping sites for H. The aim of this study is to reveal the role of individual defect types by using samples having one dominant and well-characterized defect type.

Vacancies were introduced in single crystalline W specimens by damaging with 200 keV protons to low damage levels. The samples were annealed at temperatures in the range of 500-1800 K to investigate the stages of vacancy clustering. Dislocations were introduced in recrystallized W samples via tensile plastic deformation to various strains. The resulting defects were characterized by positron annihilation lifetime spectroscopy and transmission electron microscopy. In order to fill the defects with deuterium (D), the samples were exposed to a low-flux D plasma. The D inventory in the samples was characterized by nuclear reaction analysis and thermal desorption spectroscopy. It was observed that the dislocations have a relatively small influence on the D retention, but they may facilitate the formation of blisters. Vacancies have a considerably higher D binding energy compared to dislocations. By annealing at temperatures above 600 K vacancies agglomerate in clusters, which have even higher D binding energies.