Dust–wall and dust–plasma interaction in the MIGRAINe code

Vignitchouk, Ladislas; Tolias, Panagiotis; Ratynskaia, S.

doi:10.1088/0741-3335/56/9/095005

Cited by 71 publications

(107 citation statements)

References 90 publications

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“…Furthermore, in a plasma environment, neutralization by electron impact detachment, − + → + 2 , also becomes a faster process with lower work function. Although electron impact detachment and secondary electron emission are not important processes in usual discharge plasmas they come into play in plasmas with a higher electron temperature, and can have a strong influence on dust charging both in fusion plasma devices [28] and in space plasmas [29]. …”

Section: Summary and Discussionmentioning

confidence: 99%

On the work function and the charging of small (r≤ 5 nm) nanoparticles in plasmas

et al. 2017

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On the work function and the charging of small (r <= 5 nm) nanoparticles in plasmas, Physics of Plasmas, 2017. 24 electron field emission (EFE), thermionic electron emission (TIE), and electron impact detachment. Here we report theoretical vales of the work function in this size range. Density functional theory (DFT) is used to calculate the work functions for a set of NP charge numbers, sizes and shapes, using copper for a case study. An analytical approximation is shown to give quite accurate work functions provided that >0.4 nm, i.e., consisting of about > 20 atoms, and provided also that the NPs have relaxed to close to spherical shape.For smaller sizes W deviates from the approximation, and also depends on the charge number. Some consequences of these results for nanoparticle charging are outlined. In particular, a decrease in W for NP radius below about 1 nm has fundamental consequences for their charge in a plasma environment, and thereby on the important processes of NP nucleation, early growth, and agglomeration.

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Section: Summary and Discussionmentioning

confidence: 99%

On the work function and the charging of small (r≤ 5 nm) nanoparticles in plasmas

et al. 2017

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“…The main formalism used to quantify the currents and heat fluxes driving the variations of the droplet potential and temper ature is described in detail in [21]. Here, we repeat only the basic equations and focus mainly on the parts of the MIGRAINe model which have been subject to recent updates for the calculations described in this paper.…”

Section: Droplet Charging and Heating In The Plasmamentioning

confidence: 99%

“…Simulations of droplet cooling and transport are carried out using the MIGRAINe code [19,21], which implements updated dust-plasma interaction models specifically developed to take into account the non-OML particle and heat flux collection regime, as well as to incorporate surface processes relevant for Be exposed to high-energy electrons and highly charged Ne ions. Furthermore, MIGRAINe's detailed dustwall collisions model [21,22] is employed to predict the spatial redistribution of solid dust in the plasma chamber.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, MIGRAINe's detailed dustwall collisions model [21,22] is employed to predict the spatial redistribution of solid dust in the plasma chamber. Droplet injection points are set at locations on the first wall receiving the highest heat flux during the TQ while the particle size, speed and injection angle are varied within the range of currently available experimental and theoretical constraints.…”

Section: Introductionmentioning

confidence: 99%

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Survival and in-vessel redistribution of beryllium droplets after ITER disruptions

et al. 2018

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The motion and temperature evolution of beryllium droplets produced by first wall surface melting after ITER major disruptions and vertical displacement events mitigated during the current quench are simulated by the MIGRAINe dust dynamics code. These simulations employ an updated physical model which addresses droplet-plasma interaction in ITER-relevant regimes characterized by magnetized electron collection and thin-sheath ion collection, as well as electron emission processes induced by electron and high-Z ion impacts. The disruption scenarios have been implemented from DINA simulations of the time-evolving plasma parameters, while the droplet injection points are set to the first-wall locations expected to receive the highest thermal quench heat flux according to field line tracing studies. The droplet size, speed and ejection angle are varied within the range of currently available experimental and theoretical constraints, and the final quantities of interest are obtained by weighting single-trajectory output with different size and speed distributions. Detailed estimates of droplet solidification into dust grains and their subsequent deposition in the vessel are obtained. For representative distributions of the droplet injection parameters, the results indicate that at most a few percents of the beryllium mass initially injected is converted into solid dust, while the remaining mass either vaporizes or forms liquid splashes on the wall. Simulated in-vessel spatial distributions are also provided for the surviving dust, with the aim of providing guidance for planned dust diagnostic, retrieval and clean-up systems on ITER.

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“…This dependence on the pre-history of the trajectory clearly implies that control of the impact velocity prior to sticking should be an essential ingredient of reliable remobilization experiments. For tokamak relevant materials, the sticking velocity of 1 − 10 µm grains generally lies in the range v s = 0.1 − 10 m/sec [17].…”

Section: A the Sticking Impact Regimementioning

confidence: 99%

Dust remobilization in fusion plasmas under steady state conditions

Tolias

Ratynskaia

Angeli

et al. 2016

Plasma Phys. Control. Fusion

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The first combined experimental and theoretical studies of dust remobilization by plasma forces are reported. The main theoretical aspects of remobilization in fusion devices under steady state conditions are analyzed. In particular, the dominant role of adhesive forces is highlighted and generic remobilization conditions -direct lift-up, sliding, rolling -are formulated. A novel experimental technique is proposed, based on controlled adhesion of dust grains on tungsten samples combined with detailed mapping of the dust deposition profile prior and post plasma exposure. Proof-ofprinciple experiments in the TEXTOR tokamak and the EXTRAP-T2R reversed-field pinch are presented. The versatile environment of the linear device Pilot-PSI allowed for experiments with different magnetic field topologies and varying plasma conditions that were complemented with camera observations.

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Dust–wall and dust–plasma interaction in the MIGRAINe code

Cited by 71 publications

References 90 publications

On the work function and the charging of small (r≤ 5 nm) nanoparticles in plasmas

On the work function and the charging of small (r≤ 5 nm) nanoparticles in plasmas

Survival and in-vessel redistribution of beryllium droplets after ITER disruptions

Dust remobilization in fusion plasmas under steady state conditions

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