Influence of plasma impurities on the deuterium retention in tungsten exposed in the linear plasma generator PSI-2

The hydrogen retention in fusion reactors can be significantly influenced by the presence of plasma impurities. Earlier studies showed that helium can reduce the retention in tungsten wall materials. This paper gives the results of experiments on this topic in the linear plasma generator PSI-2. Expo...

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Bibliographic Details
Published in:	Journal of nuclear materials 2015-08, Vol.463, p.1021-1024
Main Authors:	Reinhart, M., Kreter, A., Buzi, L., Rasinski, M., Pospieszczyk, A., Unterberg, B., Linsmeier, Ch
Format:	Article
Language:	eng
Subjects:	Deuterium Diffusion layers Exposure Helium Impurities Nanostructure Plasma generators Tungsten
Online Access:	Get full text
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Summary:	The hydrogen retention in fusion reactors can be significantly influenced by the presence of plasma impurities. Earlier studies showed that helium can reduce the retention in tungsten wall materials. This paper gives the results of experiments on this topic in the linear plasma generator PSI-2. Exposures of polycrystalline tungsten samples to a deuterium plasma were performed at low temperatures (380K) under the variation of the impurity species (He, Ar) and concentration (0–5%). For the experiments with He, the total deuterium fluence was varied between 2⋅1024m−2 and 2⋅1026m−2. Subsequently, the surface morphology and deuterium retention were investigated. The results show a reduction of the deuterium retention by a factor of 3 for helium, and an increase by up to 30% for argon. A diffusion model for the helium case was developed, in which a shallow layer of porous helium nanobubble structures reduces the total deuterium content.
ISSN:	0022-3115 1873-4820