Publication: DEUTERIUM RETENTION IN DENSE AND DISORDERED NANOSTRUCTURED TUNGSTEN COATINGS
Дата
2017
Авторы
OGORODNIKOVA, O. V.
RUSET, C.
DELLASEGA, D.
PEZZOLI, А.
PASSONI, M.
SUGIYAMA, К.
GASPARYAN, YU.
EFIMOV, V.
BALDEN, M.
MATERN, G.
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Аннотация
Three types of nano-structured tungsten (W) coatings were investigated in respect to deuterium (D) retention after the low-energy D plasma exposure. The D depth profile was measured up to 6 μm by nuclear reaction analysis (NRA) and the total deuterium retention was measured by thermal desorption spectros-copy (TDS). In the present work, we investigated (i) a dependence of the D retention in a W coating on substrate, (ii) a dependence of the D retention in a W coating on the nano-crystalline structure, namely, columnar-like or amor-phous-like, and (iii) the D retention at an interface between layers. It was shown that most of deuterium is trapped in the interlayer between W coating and substrate. Consequently, the D retention in the interlayer between different materials can be a concern. It was found that all types of coatings show higher D accumulation compared to bulk polycrystalline W. The disodered W coating produced by Pulsed Laser Deposition (PLD) has highest deuterium (D) concen-tration compared to dense W coating produced by Combined Magnetron Sput-tering and Ion Implantation (CMSII) technology and W coating produced by standard vacuum magnetron-sputtering (SMS) method. The lowest D concen-tration was found in SMS-W coating. No significant influence of the substrate on the D retention in coatings was found. The D retention correlates with mi-crostructure of multilayer W coating: the D retention drastically increases with decreasing the grain size. Consequently, from point of view of the hydrogen isotope retention, coarse-grained crystals are recommended for application of W-based materials in fusion devices. At the same time, coarse-grained crystals are undesirable from point of view of blister formation under the plasma expo-sure. Nano-crystalline structure of W coatings suppresses the blister formation. A compromise in the development of new promising nanostructured tungsten films is necessary to keep the hydrogen concentration at an acceptable level and reducing/preventing high density of defects at the interface between nanostruc-tured coating and substrate.
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Цитирование
DEUTERIUM RETENTION IN DENSE AND DISORDERED NANOSTRUCTURED TUNGSTEN COATINGS [Текст.] / OGORODNIKOVA O.V. [и др.] // Взаимодействие плазмы с поверхностью: сборник научных трудов XX конференции. - 2017. - С. 66