Bochum 2015 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 16: Poster Session - Helmholtz Graduate School for Plasma Physics

P 16.11: Poster

Dienstag, 3. März 2015, 16:30–18:30, Foyer Audimax

Measurements and Modelling of Hydrogen Dynamics in Tungsten — •Johannes Bauer1,2, Thomas Schwarz-Selinger1, Klaus Schmid1, Udo von Toussaint1, and Wolfgang Jacob11Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, D-85748 Garching — 2Technische Universität München, James-Franck-Str. 1, D-85748 Garching

Although hydrogen retention in defect free tungsten is low it can be significantly altered by plasma wetting. Thus understanding the interaction and dynamics of hydrogen in tungsten becomes an important issue. Present understanding distinguishes between solute and trapped hydrogen inventory. The solute hydrogen is located in the tetrahedral interstitial sites of bbc tungsten and can diffuse rapidly due to the low activation energy of 0.2-0.4 eV. The trapped hydrogen inventory resides at defects like vacancies, grain boundaries or dislocations, with de-trapping energies between 0.8-2.0 eV and is therefore less mobile. Common ex-situ experiments only allow the investigation of hydrogen retained in traps, while the solute is out of experimental reach due to its fast out-gassing at ambient temperatures. In this study the dynamics of the solute hydrogen in tungsten is measured in-situ for the first time. Diffusion/trapping simulations reveal that for low temperature e.g. 200 K, the solute hydrogen dominates the total inventory and its out-gassing after implantation is slowed down to the timescale of hours. Therefore in-situ hydrogen implantation and nuclear reaction analysis of tungsten samples are conducted at temperatures down to 140 K investigating experimentally the dynamics of solute hydrogen.

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