Design Strategy for the PFC in DEMO Reactor (KIT Scientific Reports ; 7637)

Igitkhanov, Yuri; Bazylev, B.; Landman, I.; Fetzer, Renate

doi:10.5445/ksp/1000032116

Cited by 2 publications

(1 citation statement)

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“…Some particle energies lie above the sputter threshold, while the average stays below it. Temperatures in the DEMO Scrape-Off-Layer (SOL) are expected to be below 100 eV according to [37], whereas [14] expects more than 100 eV. The design question whether high heat flux limiters will be installed still remains open for DEMO [37].…”

Section: Introductionmentioning

confidence: 99%

Preferential sputtering induced Cr-Diffusion during plasma exposure of WCrY smart alloys

Schmitz

Mutzke

Litnovsky

et al. 2019

Journal of Nuclear Materials

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Section: Introductionmentioning

confidence: 99%

Preferential sputtering induced Cr-Diffusion during plasma exposure of WCrY smart alloys

Schmitz

Mutzke

Litnovsky

et al. 2019

Journal of Nuclear Materials

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On Oxidation Resistance Mechanisms at 1273 K of Tungsten-Based Alloys Containing Chromium and Yttria

Klein

Wegener

Litnovsky

et al. 2018

Metals

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Tungsten (W) is currently deemed the main candidate for the plasma-facing armor material of the first wall of future fusion reactors, such as DEMO. Advantages of W include a high melting point, high thermal conductivity, low tritium retention, and low erosion yield. However, was an accident to occur, air ingress into the vacuum vessel could occur and the temperature of the first wall could reach 1200 K to 1450 K due to nuclear decay heat. In the absence of cooling, the temperature remains in that range for several weeks. At these temperatures, the radioactive tungsten oxidizes and then volatilizes. Smart W alloys are therefore being developed. Smart alloys are supposed to preserve properties of W during plasma operation while suppressing tungsten oxide formation in case of an accident. This study focuses on investigations of thin film smart alloys produced by magnetron sputtering. These alloys provide an idealistic system with a homogeneous distribution of the elements W, chromium (Cr), and yttrium (Y) on an atomic scale. The recommended composition is W with 12 weight % of Cr and 0.5 weight % of Y. Passivation and a suppression of WO 3 sublimation is shown. For the first time, the mechanisms yielding the improved oxidation resistance are analyzed in detail. A protective Cr 2 O 3 layer forms at the surface. The different stages of the oxidation processes up to the failure of the protective function are analyzed for the first time. Using 18 O as a tracer, it is shown for the first time that the oxide growth occurs at the surface of the protective oxide. The Cr is continuously replenished from the bulk of the sample, including the Cr-rich phase which forms during exposure at 1273 K. A homogenous distribution of yttria within the W-matrix, which is preserved during oxidation, is a peculiarity of the analyzed alloy. Further, an Y-enriched nucleation site is found at the interface between metal and oxide. This nucleation sites are deemed to be crucial for the improved oxidation resistance.

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Design Strategy for the PFC in DEMO Reactor (KIT Scientific Reports ; 7637)

Cited by 2 publications

References 0 publications

Preferential sputtering induced Cr-Diffusion during plasma exposure of WCrY smart alloys

Preferential sputtering induced Cr-Diffusion during plasma exposure of WCrY smart alloys

On Oxidation Resistance Mechanisms at 1273 K of Tungsten-Based Alloys Containing Chromium and Yttria

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