Regensburg 2010 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 22: Hydrogen in Metals

MM 22.5: Talk

Tuesday, March 23, 2010, 11:15–11:30, H5

Effects of recrystallization on the deuterium retention in tungsten — •Armin Manhard and Klaus Schmid — Max-Planck-Institut für Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching

Tungsten is a promising material for plasma-facing surfaces in nuclear fusion devices such as ITER. In these machines the surface material is exposed to large fluxes and fluences of hydrogen isotope ions and energetic neutrals. The retention of hydrogen isotopes in tungsten is generally considered small. The underlying mechanisms are yet only poorly understood despite continued research efforts. Especially the microstructure of the material can have a large influence on the hydrogen inventory.

To investigate this, the microstructure of tungsten samples from the same base material is systematically modified by recrystallization. After a thorough characterization by electron microscopy, strongly deformed samples and samples recrystallized by different degrees are loaded with deuterium in a low-temperature plasma device. The ion energy is adjusted by sample biasing. The deuterium inventory is then measured by nuclear reaction analysis and thermal effusion spectroscopy. The surface morphology is investigated by optical and atomic force microscopy. Microscopic markers applied to the sample surface allow to observe the identical surface region after each treatment step. The results are presented and compared for the different microstructures.