Survey of dust formed in the TEXTOR tokamak: structure and fuel retention

Ivanova, Darya; Rubel, M.; Philipps, V.; Freisinger, M.; Huang, Z. Rena; Penkalla, H. J.; Schweer, B.; Sergienko, G.; Sundelin, Per; Wessel, E.

doi:10.1088/0031-8949/2009/t138/014025

Cited by 27 publications

(21 citation statements)

References 24 publications

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“…Although both collection techniques are applied by different research groups on several devices (e.g. [2,[19][20][21][22]24,25,28,29,33]), collection efficiency assessments are missing.…”

Section: 53mentioning

confidence: 99%

Collection strategy, inner morphology, and size distribution of dust particles in ASDEX Upgrade

et al. 2014

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Abstract.The dust collection and analysis strategy in ASDEX Upgrade (AUG) is described. During five consecutive operation campaigns (2007)(2008)(2009)(2010)(2011), Si collectors were installed, which were supported by filtered vacuum sampling and collection with adhesive tapes in 2009. The outer and inner morphology (e.g. shape) and elemental composition of the collected particles were analysed by scanning electron microscopy. The majority of the ~50000 analysed particles on the Si collectors of campaign 2009 contain tungsten -the plasma-facing material in AUG -and show basically two different types of outer appearance: spheroids and irregularly shaped particles. By far most of the W-dominated spheroids consist of a solid W core, i.e., solidified W droplets. A part of these particles is coated with low Z material; a process which seems to happen presumably in the far scrape off layer plasma. In addition, some conglomerates of B, C, and W appear as spherical particles after their contact with plasma. By far most of the particles classified as B-, C-, and W-dominated irregularly shaped particles consist of the same conglomerate with varying fraction of embedded W in the B-C matrix and some porosity, which can exceed 50%. The fragile structures of many conglomerates confirm the absence of intensive plasma contact. Both the ablation and mobilization of conglomerate material and the production of W droplets are proposed to be triggered by arcing. The size distribution of each dust particle class is best described by a lognormal distribution allowing an extrapolation of the dust volume and surface area. The maximum in this distribution is observed above the resolution limit of 0.28 µm only for the W-dominated spheroids, at around 1 µm. The amount of W-containing dust is extrapolated to be less than 300 mg on the horizontal areas of AUG.

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“…Although both collection techniques are applied by different research groups on several devices (e.g. [2,[19][20][21][22]24,25,28,29,33]), collection efficiency assessments are missing.…”

Section: 53mentioning

confidence: 99%

Collection strategy, inner morphology, and size distribution of dust particles in ASDEX Upgrade

et al. 2014

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“…the deuterium-to-carbon concentration ratio (D/C) is about 0.1, as studied in detail after several long-term campaigns in TEXTOR [13,17,18]. The micrograph in figure 2(a) demonstrates an SEM image of the limiter surface with deposits (as retrieved from TEXTOR), whereas the limiter surface after annealing at up to 1273 K is shown in figure 2(b).…”

Section: Resultsmentioning

confidence: 99%

“…Plots in figures 3(a) and (b) show thermal desorption spectra for deposits from ALT-II; for more details of such deposits, see [18]. The release of species with mass 3, 4, 19 and 20 is plotted: HD (M3), D 2 (M4), M19 and M20, which represent a mixture of C 1 hydrocarbons and deuterated water (HDO, D 2 O).…”

Section: Exposure In Padosmentioning

confidence: 99%

Fuel re-absorption by thermally treated co-deposited carbon layers

Ivanova¹,

Rubel²,

Philipps³

et al. 2011

Phys. Scr.

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Systematic studies have been conducted to address the fuel re-absorption by carbon deposits under repeated exposure to plasma after cleaning procedures. The investigation was done with graphite tiles from ALT-II (Advanced Limiter Test II), i.e. the main limiter at the TEXTOR tokamak. Pure graphite plates were used as the reference material. The experimental programme comprised the following: pre-characterization of specimens; D desorption by baking the tile at 1273 K; surface analyses of the fuel-depleted layers; exposure to deuterium in a laboratory plasma device and in TEXTOR; and quantitative assessment of deuterium re-absorption. The main result is that fuel retention in the re-exposed deposits is 30-40 times lower than that in the original co-deposit, showing that fuel re-absorption does not lead to an immediate re-saturation of deposits. Annealing at high temperatures enhances layer brittleness, leading eventually to detachment of co-deposits.

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“…Средняя площадь каждой отслоившейся пластинки составляла примерно 30×30 мкм (на одну микродугу). Следует о т-метить, что в Т-10 [5] и других токамаках [2,3] не было обнаружено таких металлических частиц, как в токамаке Глобус-М. По нашему мнению, образование пластин происходило из-за накопления углерода и кислорода в поверхностном слое нержавеющей стали и возникновения механических напряжений и, соответс т-венно, деформаций.…”

Section: экспериментальные результаты и их обсуждениеunclassified

“…В настоящее время наиболее перспективными термоядерными материалами считаются бериллий, углеродные композиты и вольфрам [1]. Одной из методик выбора материала является анализ пыли и крупных частиц (в английской литературе «dust» и «debris»), образующихся в токамаках в процессе их эксплуатации [2]. Углеродная и бериллиевая пыль является сильным аккумулятором трития, затрудняющим его дальнейшее использование в термоядерном цикле [3].…”

Section: Introductionunclassified