Characterization and origin of large size dust particles produced in the Alcator C-Mod tokamak

Arnas, C.; Irby, J.; Celli, S.; Temmerman, G. De; Addab, Y.; Couëdel, Lénaïc; Grisolia, Christian; Lin, Y.; Martin, Céline; Pardanaud, C.; Pierson, S.

doi:10.1016/j.nme.2017.02.027

Cited by 20 publications

(16 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Beryllium particulate ejection has also been observed as a result of disruptions in JET equipped with its ITER-Like Wall, illustrating that even at comparatively low stored energies, Be melting can and does occur [11]. Post-mortem examination of in-vessel surfaces and of PFCs extracted from the machine clearly show the presence of re-solidified droplets in the vicinity of melted regions (similar observations have also been made on molybdenum tiles in Alcator C-Mod [12]). …”

Section: Introductionsupporting

confidence: 54%

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

et al. 2018

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionsupporting

confidence: 54%

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

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, experiments have shown that the combination of different phenomena (e.g. melting of edges of PFC, material fatigue, intense particle fluxes, material erosion followed by accretion in the plasma edge, …), particularly during off normal events such as Edge Localized Modes (ELMs) or disruptions, can trigger the formation in the plasma chamber of particles with variable size, ranging from tens of nanometers to hundreds of micrometers [2,3,4,5]. Due to expected much higher energy outflows in ITER compared to the currently operating tokamaks, larger quantities of dust could be produced.…”

Section: Introductionmentioning

confidence: 99%

Design of model tokamak particles for future toxicity studies: Morphology and physical characterization

Bernard

Jambon

Georges

et al. 2019

Fusion Engineering and Design

Self Cite

View full text Add to dashboard Cite

During ITER operation, it is expected that the large panel of plasma-wall interactions triggers the production of dust particles, potentially loaded with tritium present nearby. Tritium (T) inventory in the various materials, such as tungsten (W), is of prime importance for the safety assessment of a Tokamak machine, and it is even more crucial when considering dispersible matters like dusts: in case of a Loss Of Vacuum Accident (LOVA), dusts may form aerosols containing tritium and activation products that could escape the first confinement barrier and be released in the environment. The with tritium inventory in the described W dusts and their suspension in various liquid media for cell exposure for toxicity studies.

show abstract

“…Outwith astrophysics, in magnetically confined fusion, material sputtered from the vessel walls has an elongated geometry (e.g. Arnas et al (2017)) and can disrupt the optimum operation of the device when it migrates through the plasma. Understanding the growth and evolution of such dust can help mitigate disruption and enhance operation.…”

Section: Discussionmentioning

confidence: 99%

Evolution of spheroidal dust in electrically active sub-stellar atmospheres

Stark,

Diver

2020

Preprint

View full text Add to dashboard Cite

Context. Understanding the source of sub-stellar polarimetric observations in the optical and near-infrared is key to characterizing sub-stellar objects and developing potential diagnostics for determining properties of their atmospheres. Differential scattering from a population of aligned, non-spherical dust grains is a potential source of polarization that could be used to determine geometric properties of the dust clouds. Aims. This paper addresses the problem of the spheroidal growth of dust grains in electrically activated sub-stellar atmospheres. It presents the novel application of a mechanism whereby non-spherical, elongated dust grains can be grown via plasma deposition as a consequence of the surface electric field effects of charged dust grains. Methods. We numerically solve the differential equations governing the spheroidal growth of charged dust grains via plasma deposition as a result of surface electric field effects in order to determine how the dust eccentricity and the dust particle eccentricity distribution function evolve with time. From these results, we determine the effect of spheroidal dust on the observed linear polarization.Results. Numerical solutions show that e ≈ 0.94 defines a watershed eccentricity, where the eccentricity of grains with an initial eccentricity less than (greater than) this value decreases (increases) and spherical (spheroidal) growth occurs. This produces a characteristic bimodal eccentricity distribution function yielding a fractional change in the observed linear polarization of up to ≈ 0.1 corresponding to dust grains of maximal eccentricity at wavelengths of ≈ 1µm, consistent with the near infrared observational window. Order of magnitude calculations indicate that a population of aligned, spheroidal dust grains can produce degrees of polarization P ≈ O(10 −2 − 1%) consistent with observed polarization signatures. Conclusions. The results presented here are relevant to the growth of non-spherical, irregularly shaped dust grains of general geometry where non-uniform surface electric field effects of charged dust grains are significant. The model described in this paper may also be applicable to polarization from galactic dust and dust growth in magnetically confined plasmas.

show abstract

Characterization and origin of large size dust particles produced in the Alcator C-Mod tokamak

Cited by 20 publications

References 36 publications

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

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

Design of model tokamak particles for future toxicity studies: Morphology and physical characterization

Evolution of spheroidal dust in electrically active sub-stellar atmospheres

Contact Info

Product

Resources

About