Material mixing on plasma-facing components : Compound formation

• Two different tungsten limiters (castellated bulk metal block and W-coated graphite), subjected to high power loads in the TEXTOR tokamak, were examined in order to determine chemical composition of deposits inside the castellated grooves and on side surfaces of the coated limiter. Comprehensive analyses carried out by X-ray diffraction, ion beam analysis and other methods revealed: (i) the formation of tungsten oxide (WO2) inside the castellated grooves: (ii) the formation of tungsten carbides (WC main phase and traces of W2C) on side surfaces of the coated limiter. Elemental tungsten was found in deposits on side surfaces only in trace quantities thus indicating that tungsten eroded from the limiter top and transported to the scrape-off layer reacted with carbon. Based on thermodynamic data, the pathways leading to the formation of compounds are discussed.

Ämnesord

NATURVETENSKAP  -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)

Nyckelord

FUEL INVENTORY

TUNGSTEN COATINGS

LIMITERS

CODEPOSITION

RETENTION

BERYLLIUM

DIVERTOR

DEVICES

CARBON

Plasma physics

Plasmafysik

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