Observation of dust particles by a laser scattering method in the JIPPT-IIU tokamak

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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“…In the model, the equations of motion Eqs. (11)(12)(13)(14) are coupled to the equations for the dust radius Eq. (25), enthalpy Eqs.…”

Section: The Dustt Codementioning

confidence: 99%

Dust-particle transport in tokamak edge plasmas

Pigarov

Krasheninnikov

Soboleva³

et al. 2005

Physics of Plasmas

140

120

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“…2-D imaging techniques [2] can record the dust trajectories and dust velocity can be estimated, but there is usually no way to determine the dust size. Scattering techniques [3,8] can only resolve the size of very small particles, and can not determine velocities. Besides, dust observation events are comparatively rare, on the average often less than one event per plasma discharge.…”

Section: Introductionmentioning

confidence: 99%

“…The situation can be meliorated by introducing dust of know composition and size into divertor or scrape-off layer (SOL) and tracing its migration. Experiments with externally introduced dust have been previously performed in JIPPT-IIU tokamak [3], where micron size carbon dust was spread from the top of the vacuum chamber and detected by Thomson scattering. No noticeable effect on the plasma was observed for dust falls of up to at least 10 6 particles (10 µg) in 20 ms during discharges.…”

Section: Introductionmentioning

confidence: 99%

Migration of artificially introduced micron-size carbon dust in the DIII-D divertor

Rudakov

West

Wong

et al. 2007

Journal of Nuclear Materials

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Migration of pre-characterized carbon dust in a tokamak environment was studied by introducing about 30 milligrams of dust flakes 5-10 µm in diameter in the lower divertor of DIII-D using the DiMES sample holder. The dust was exposed to high power ELMing Hmode discharges in lower-single-null magnetic configuration with the strike points swept across the divertor floor. When the outer strike point (OSP) passed over the dust holder exposing it to high particle and heat fluxes, part of the dust was injected into the plasma. In about 0.1 sec following the OSP pass over the dust, 1-2% of the total dust carbon content (2- 4×1019 carbon atoms, equivalent to a few million dust particles) penetrated the core plasma, raising the core carbon density by a factor of 2-3. When the OSP was inboard of the dust holder, the dust injection continued at a lower rate. Individual dust particles were observed moving at velocities of 10-100 m/s, predominantly in the toroidal direction for deuteron flow to the outer divertor target, consistent with the ion drag force. The observed behavior of the dust is in qualitative agreement with modeling by the 3D DustT code.2

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“…Actually, most OPC techniques use the Lorenz-Mie theory, and its simple spherical particle model (homogeneous [4] or multilayered [5]), to perform light scattering calculations. If this particle model is suitable for most droplets and bubbly flows [6,7], it may be questionable when dealing with some dusty [8][9][10][11][12][13] or fusion [1,3,[14][15][16][17] plasmas where the shape of the particles is more chain-like, cauliflower-like or flake-like. The inversion technique and the regularization scheme are also key factors for reliable and accurate measurements [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

On the Optical Characterisation of Nanoparticle and their Aggregates in Plasma Systems

Onofri

Woźniak

Barbosa

2011

Contrib. Plasma Phys.

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International audienceThis paper outline and discuss basic considerations for the optical characterization of nanoparticles and their aggregates: particle models, light scattering theories and main experimental setups, regarding their interest for the study of plasma flows. It emphasizes that there are now powerful alternatives to the Lorenz-Mie theory and its simple homogeneous sphere model, which allow accurate calculations of the optical properties of particles with complex sub-structures and shapes. (c) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

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Observation of dust particles by a laser scattering method in the JIPPT-IIU tokamak

Cited by 61 publications

References 9 publications

Dust-particle transport in tokamak edge plasmas

Dust-particle transport in tokamak edge plasmas

Migration of artificially introduced micron-size carbon dust in the DIII-D divertor

On the Optical Characterisation of Nanoparticle and their Aggregates in Plasma Systems

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