Deposition of impurity metals during campaigns with the JET ITER-like Wall

Widdowson, A.; Coad, J. P.; Alves, E.; Baron-Wiechec, A.; Catarino, N.; Corregidor, V.; Heinola, K.; Krat, S.; Makepeace, C.; Matthews, G. F.; Mayer, M.; Mizohata, Kenichiro; Sertoli, M.

doi:10.1016/j.nme.2018.12.024

Cited by 24 publications

(28 citation statements)

References 20 publications

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“…Ion Beam Analysis (IBA) has also shown increased amounts of Ni on Tile 1 [6]. Iron (Fe) and chromium (Cr) were not measured with SIMS, but ratios of Ni, Fe and Cr from ion beam measurements suggest that Ni, Fe and Cr on the deposits is from the main chamber Inconel components eroded by the charge exchange neutrals (CXN) [6]. W is mainly eroded from the outer divertor tiles, but CXN erosion of W coated surfaces of main chamber wall acts also as a W source [6].…”

Section: Resultsmentioning

confidence: 99%

“…Iron (Fe) and chromium (Cr) were not measured with SIMS, but ratios of Ni, Fe and Cr from ion beam measurements suggest that Ni, Fe and Cr on the deposits is from the main chamber Inconel components eroded by the charge exchange neutrals (CXN) [6]. W is mainly eroded from the outer divertor tiles, but CXN erosion of W coated surfaces of main chamber wall acts also as a W source [6]. After ILW-2, which had a similar strike distribution as ILW-3, clear erosion was observed on tiles 5 and 6 and small erosion on tiles 7 and 8 [7].…”

Section: Resultsmentioning

confidence: 99%

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Deuterium retention on the tungsten-coated divertor tiles of JET ITER-like wall in 2015–2016 campaign

Lahtinen

Likonen

Koivuranta

et al. 2019

Fusion Engineering and Design

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Tungsten-coated divertor tiles exposed during the third JET ITER-Like Wall (ILW) campaign in were studied with Secondary Ion Mass Spectrometry (SIMS). ILW-3 campaign contained more high-power plasma discharges and longer plasma time than the earlier ILW campaigns. Measurements showed increased beryllium (Be) deposition on the upper inner divertor, whereas on the outer divertor, Be deposition was lower than during the second campaign in 2013-2014 (ILW-2). Increased intensities of nickel, molybdenum and tungsten were observed at the surface layer of the inner divertor Be dominated deposits. These layers are probably formed during the high-power plasma discharge phase near the end of the ILW-3 campaign. Compared to the earlier campaigns, D retention on the upper inner divertor was observed to on a similar level than after ILW-2, whereas at the lower inner divertor and most parts of the outer divertor, D retention was lower for ILW-3 than ILW-2. D retention was increased at lower part of outer divertor Tile 7, where Be deposition was slightly increased. Probable reason for the reduction is the higher surface temperature of the tiles due to higher powers used.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Deuterium retention on the tungsten-coated divertor tiles of JET ITER-like wall in 2015–2016 campaign

Lahtinen

Likonen

Koivuranta

et al. 2019

Fusion Engineering and Design

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“…An alternative approach is to look at the mid and high atomic number (Z) impurities seen in the deposited layer to establish the deposition pattern. In JET the common mid and high-Z impurities are Ni, iron (Fe) and chromium (Cr) which derive from erosion of the Inconel® outer vessel wall by charge exchange neutrals (CXNs) and also W coming from main chamber and divertor erosion [24]. Indeed Ni and W are seen on the surfaces of all limiter tiles around the vessel at low concentrations ~10 17 atoms/cm 2 [2].…”

Section: Erosion and Deposition Materials Migrationmentioning

confidence: 99%

Fuel inventory and material migration of JET main chamber plasma facing components compared over three operational periods

et al. 2020

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Fuel retention and material migration results from JET ITER-like wall beryllium limiter tiles are presented for three operating periods. Ion beam analysis results support the general picture of erosion during limiter configurations with local deposition on tile ends far into the scrape off layer. Similar trends of fuel concentrations are observed in all JET operating periods; (i) low on surfaces exposed to high heat flux and erosion and (ii) higher in deposits. The pattern of fuel retention and deposition correlates with heat flux and distribution of limiter plasmas touching inner and outer limiters. The D/Be ratio in the thickest deposit is ~0.01. Global fuel retention attributed to limiters is < 0.01% of injected fuel. Marker coatings reveal a rapid transition from strong erosion to deposition within 15 mm. This work highlights the need to carefully consider the requirements of marker coatings for long exposure studies in high erosion areas.

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“…This contribution is devoted to the investigation of D retention in Be-W-D codeposited layers of various composition. The emphasis is put on studying layers with low W content (< 30%), similarly to the layers found in JET (≤ 10%) [3] and to layers that can be expected in ITER. The effect of gas pressure during deposition is also investigated with the effort in obtaining data at high pressures, which will be preferred in the ITER divertor for power handling reasons [26].…”

Section: Introductionmentioning

confidence: 99%

Deuterium retention in mixed Be-W-D codeposited layers

et al. 2020

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Mixed beryllium-tungsten-deuterium (Be-W-D) layers (4.4-28.4 at.% W) were codeposited in a magnetron discharge in D 2 -Ar atmosphere at pressures of 0.8 Pa, 2.7 Pa, and 8 Pa and a substrate temperature of 373 ± 15 K. The composition of the layers was determined using nuclear reaction analysis and Rutherford backscattering spectrometry. D trapping states in the layers were examined using thermal desorption spectroscopy. At all pressures used, the D concentration in the layers has a nonmonotonic dependence on the W concentration, with the maximum occurring at 4.4-7.3% W. In this case, the D concentration is about two times greater than that in a Be-D layer; in W-D layers the D concentration is more than one order of magnitude smaller. Increase of pressure during deposition results in an increase of the D concentration in Be-D and Be-W-D (4.4-7.3% W) layers and is linked with the appearance of sharp low-temperature D release peaks near 450 K and 500 K. Increase of pressure also results in steeper decrease of the D concentration with increasing W concentration beyond 7.3%. It is concluded that for the layers deposited at 450 K and above, the effect of the presence of W (4.4-28.4%) on the D retention becomes small.

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Deposition of impurity metals during campaigns with the JET ITER-like Wall

Cited by 24 publications

References 20 publications

Deuterium retention on the tungsten-coated divertor tiles of JET ITER-like wall in 2015–2016 campaign

Deuterium retention on the tungsten-coated divertor tiles of JET ITER-like wall in 2015–2016 campaign

Fuel inventory and material migration of JET main chamber plasma facing components compared over three operational periods

Deuterium retention in mixed Be-W-D codeposited layers

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