Dust and flakes in the JET MkIIa divertor, analysis and results

Peacock, Alan T.; Andrew, P.; Cetier, Ph.; Coad, J.P.; Federici, G.; Hurd, F.; Pick, M.; Wu, Cheng-Hsuan

doi:10.1016/s0022-3115(98)00670-9

Cited by 87 publications

(73 citation statements)

References 3 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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“…Such a technique of dust preparation was successfully applied earlier in DIII-D [5]. The dust holder had a diameter of 25 mm and a spherical cavity of ~ 0.7 mm in its deepest point.…”

Section: Preparations For Dust Launchmentioning

confidence: 99%

Dust investigations in TEXTOR: Impact of dust on plasma–wall interactions and on plasma performance

Litnovsky

Rudakov

Bozhenkov

et al. 2013

Journal of Nuclear Materials

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Dust will have severe impact on ITER performance since the accumulation of tritium in dust represents a safety issue, a possible reaction of dust with air and steam imposes an explosion 2 hazard and the penetration of dust in core plasmas may degrade plasma performance by increasing radiative losses. Investigations were performed in TEXTOR where known amounts of pre-characterized carbon, diamond and tungsten dust were mobilized into plasmas using special dust holders.Mobilization of dust changed a balance between plasma-surface interactions processes, significantly increasing net deposition. Immediately after launch dust was dominating both core and edge plasma parameters. Remarkably, in about 100 milliseconds after the launch, the effect of dust on edge and core plasma parameters was vanished: no increase of carbon and tungsten concentrations in the core plasmas was detected suggesting a prompt transport of dust to the nearby plasma-facing components without further residence in the plasma. PSI 2012

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“…[5][6][7][8][9][10][11]), dust particles of 10 nm -100 µm in size are unavoidably present in all fusion devices (as well as larger flakes and loose co-deposited layers of a millimeter and more). Routine analysis [6][7][8][9][10] of dust collected after the vent-to-air in many tokamaks and stellarators give insight into dust distributions, characteristics, and total mass. This analysis indicates that dust particles are comprised mainly of the plasma facing component (PFC) materials used in these machines.…”

Section: Introductionmentioning

confidence: 99%

Dust-particle transport in tokamak edge plasmas

Pigarov

Krasheninnikov

Soboleva³

et al. 2005

Physics of Plasmas

140

120

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Dust particulates in the size range of 10nm-100µm are found in all fusion devices. Such dust can be generated during tokamak operation due to strong plasma/material-surface interactions. Some recent experiments and theoretical estimates indicate that dust particles can provide an important source of impurities in the tokamak plasma. Moreover, dust can be a serious threat to the safety of next-step fusion devices. In this paper, recent experimental observations on dust in fusion devices are reviewed. A physical model for dust transport simulation, and a newly developed code DUSTT, are discussed. The DUSTT code incorporates both dust dynamics due to comprehensive dust-plasma interactions as well as the effects of dust heating, charging, and evaporation. The code tracks test dust particles in realistic plasma backgrounds as provided by edge-plasma transport codes. Results are presented for dust transport in current and next-step tokamaks. The effect of dust on divertor plasma profiles and core plasma contamination is examined.3

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Dust and flakes in the JET MkIIa divertor, analysis and results

Cited by 87 publications

References 3 publications

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

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

Dust investigations in TEXTOR: Impact of dust on plasma–wall interactions and on plasma performance

Dust-particle transport in tokamak edge plasmas

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