Dust in magnetic fusion devices

Krasheninnikov, S. I.; Smirnov, R.D.; Rudakov, D.L.

doi:10.1088/0741-3335/53/8/083001

Cited by 192 publications

(154 citation statements)

References 212 publications

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“…The heat flux density p rad due to the radiation from the particle's surface is given by p rad =-σ×T 4 , with σ=5.67×10 -8 W/(m 2 K 4 ). Of course the particle also receives thermal radiation from the wall as well as from the main plasma.…”

Section: The Heatingmentioning

confidence: 99%

“…If arcs are burning at the first wall liquid particles as a typical product of arc erosion will be ejected from the typical craters (figure 1) into the SOL [1,2,3,4,5]. During its flight through the plasma the particles will be evaporated [6,7] introducing wall material into the SOL and, eventually, some may even cross the LCFS thereby injecting a fraction of the impurity material into the confined central plasma column.…”

Section: Introductionmentioning

confidence: 99%

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Modification of arc emitted W particles in a model scrape-off layer plasma

Laux

Balden

Siemroth³

2014

Phys. Scr.

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Abstract. In fusion machines (like e.g. ASDEX Upgrade and JET) equipped with W-coated plasma facing components (PFCs) arc tracks are observed post-mortem and W-particles are identified as a component of the dust. Results from laboratory arcing of W-coated PFC-material concerning the size, velocity, and direction of macro-particles are combined with model calculations of the heating, cooling, and evaporation of W particles flying through a simplified scrape-off layer (SOL) plasma to assess the role of arc produced particles as a source of W-impurities. W atoms or ions eroded from a macro-particle flying across the SOL plasma are not subject to prompt re-deposition onto a PFC. Therefore, macro-particles constitute an essential source of W in the SOL and even may result in an impurity input into the region of confined plasma if the particle succeeds to path the SOL and cross the last closed flux surface (LCFS). The main result of the modelling is that a W-particle from the large-size end of the distribution obtained in laboratory arcing and having a typical velocity (also known from laboratory experiment) is able to pass a SOL of 10cm thickness filled with a realistic plasma and, finally, inject a certain amount of Wmaterial into the confined plasma region.

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Section: The Heatingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modification of arc emitted W particles in a model scrape-off layer plasma

Laux

Balden

Siemroth³

2014

Phys. Scr.

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“…Dust particles are normally not a concern in current short-pulse tokamaks where the energy fluxes to the walls are relatively moderate (a reference number is q ref = 1 MW/m 2 ), although occasionally a big chunk of material released by the wall can trigger a disruption [11]. However, long-pulse machines like ITER or DEMO are characterized by much higher energy fluxes (q ref = 10 MW/m 2 ), stronger plasma-material interaction and are estimated to produce hundreds kg of dust.…”

Section: Introductionmentioning

confidence: 99%

Survivability of dust in tokamaks: Dust transport in the divertor sheath

Delzanno

Tang

2014

Physics of Plasmas

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The survivability of dust being transported in the magnetized sheath near the divertor plate of a tokamak and its impact on the desired balance of erosion and redeposition for a steady-state reactor are investigated. Two different divertor scenarios are considered. The first is characterized by an energy flux perpendicular to the plate q 0 1 MW/m 2 typical of current short-pulse tokamaks.The second has q 0 10 MW/m 2 and is relevant to long-pulse machines like ITER or DEMO.It is shown that micrometer dust particles can survive rather easily near the plates of a divertor plasma with q 0 1 MW/m 2 because thermal radiation provides adequate cooling for the dust particle. On the other hand, the survivability of micrometer dust particles near the divertor plates is drastically reduced when q 0 10 MW/m 2 . Micrometer dust particles redeposit their material non-locally, leading to a net poloidal mass migration across the divertor. Smaller particles (with radius ∼ 0.1 µm) cannot survive near the divertor and redeposit their material locally. Bigger particle (with radius ∼ 10 µm) can instead survive partially and move outside the divertor strike points, thus causing a net loss of divertor material to dust accumulation inside the chamber and some non-local redeposition. The implications of these results for ITER are discussed.

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“…The production of PLD contaminants was directed towards the realization of C deposits similar to those found in nowadays tokamaks [11][12][13][14]. Their properties depend on both the specific characteristics of the tokamak and the position within the first wall where the deposit builds up.…”

Section: Contaminants Depositionmentioning

confidence: 99%

Laser cleaning of diagnostic mirrors from tokamak-like carbon contaminants

Maffini

Uccello

Dellasega

et al. 2015

Journal of Nuclear Materials

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This paper presents a laboratory-scale experimental investigation of laser cleaning of diagnostic First Mirrors (FMs). Redeposition of contaminants sputtered from tokamak first wall onto FMs surface could dramatically decrease their reflectivity in an unacceptable way for the functioning of the plasma diagnostic systems. Laser cleaning is a promising solution to tackle this issue. In this work, pulsed laser deposition was exploited to produce rhodium films functional as FMs and to deposit onto them carbon contaminants with tailored features, resembling those found in tokamaks. The same laser system was also used to perform laser cleaning experiments by means of a sample handling procedure that allows to clean some cm 2 in few minutes. The cleaning effectiveness was evaluated in terms of specular reflectivity recovery and mirror surface integrity. The effect of different laser wavelengths (λ = 1064, 266 nm) on the cleaning process is also addressed.

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Dust in magnetic fusion devices

Cited by 192 publications

References 212 publications

Modification of arc emitted W particles in a model scrape-off layer plasma

Modification of arc emitted W particles in a model scrape-off layer plasma

Survivability of dust in tokamaks: Dust transport in the divertor sheath

Laser cleaning of diagnostic mirrors from tokamak-like carbon contaminants

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