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- Psoda, M., et al.
(författare)
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Material mixing on plasma-facing components : Compound formation
- 2009
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Ingår i: Journal of Nuclear Materials. - : Elsevier. - 0022-3115 .- 1873-4820. ; 386-388, s. 740-743
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
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| 3. |
- Sergienko, G., et al.
(författare)
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Experience with bulk tungsten test-limiters under high heat loads : melting and melt layer propagation
- 2007
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Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T128, s. 81-86
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Tidskriftsartikel (refereegranskat)abstract
- The paper provides an overview of processes and underlying physics governing tungsten melt erosion in the fusion plasma environment. Experiments with three different bulk tungsten test-limiters were performed in TEXTOR: (i) thermally insulated solid plate fixed on a graphite roof-like limiter heated up by the plasma to the melting point, (ii) macro-brush of the ITER-relevant castellated structure and (iii) lamellae structure developed for the JET divertor. The main objectives were to determine the metal surface damage, the formation of the melt layer and its motion in the magnetic field. PHEMOBRID-3D and MEMOS-1.5D numerical codes were used to simulate the experiment with the roof-like test-limiter. Both experiments and simulation showed that the melting of tungsten can lead to a large material redistribution due to thermo-electron emission currents without ejection of molten material to the plasma.
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