Secondary emission from dust grains with a surface layer: comparison between experimental and model results

Richterová, I.; Pavlu, Jiri; Němeček, Zdenek; Šafránková, Jana; Žilavý, P.

doi:10.1016/j.asr.2005.02.027

Cited by 6 publications

(5 citation statements)

References 10 publications

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“…On the other hand, a number of problems was successfully solved or elucidated in course of the last decade. The behavior of primary electrons inside the dust grain is well described by the model [82,88] and their spectra (when leaving the grain) can be computed for different materials [85,92]. We know that the grain surface potential established by secondary emission depends neither on the work function nor on the secondary emission yield but rises with the mean atomic number of the grain material [60].…”

Section: Discussionmentioning

confidence: 99%

“…However, the layer of surface impurities was not defined in this case. Thus, we have used MF (melamine-formaldehyde resin) 2.35 μm spheres covered with ≈ 20 nm of the Ni layer and adapted the model of the secondary emission [82] (see section 4) and analyzed the effects of the layer thickness [92]. It was found that the secondary emission yield increases with the thickness of the layer until a saturation is reached.…”

Section: Influence Of Surface Layersmentioning

confidence: 99%

“…The heavy line represents the pure MF grain. (Reprinted from[92], c (2006), with permission from Elsevier.)Fig. 16 A comparison of the model result and experimental data for pure MF and Ni covered MF grains.…”

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confidence: 99%

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Dust Charging in Space‐related Laboratory Experiments: A Review Focused on Secondary Emission

Pavlu

Šafránková

Němeček

et al. 2009

Contrib. Plasma Phys.

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A role of dust in the space environment is of increasing interest in the recent years. Also the fast development of fusion devices with magnetic confinement brought new issues in the plasma-surface interaction. While there is a number of dusty plasma reviews, the present paper surveys experimental results connected with charging of dust grains under well-defined laboratory conditions for both space and industrial applications. The main purpose of these experiments is to study particular charging/discharging processes preferably on spacerelated (i.e., all sorts of glass and other oxides) as well as on elemental materials (carbon, nickel, gold). Single micrometer-sized spherical grains or grain's clusters stored in vacuum are exposed to electron and ion beams. Among several charging processes, the secondary emission is discussed in broad details because this process plays a prominent role everywhen a portion of energetic electrons is present in the medium surrounding a particular grain.

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Section: Discussionmentioning

confidence: 99%

Section: Influence Of Surface Layersmentioning

confidence: 99%

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Dust Charging in Space‐related Laboratory Experiments: A Review Focused on Secondary Emission

Pavlu

Šafránková

Němeček

et al. 2009

Contrib. Plasma Phys.

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“…Thus, the charge of micrometer-sized grains can be either positive or negative and the charge sign depends on their shape, dimensions, and material. 5 Ion impacts may also induce the emission of secondary electrons, however, with a much lower yield and thus this effect is negligible in most environments.…”

Section: Introductionmentioning

confidence: 99%

Interaction between single dust grains and ions or electrons: laboratory measurements and their consequences for the dust dynamics

et al. 2008

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The present paper reviews our latest, and brings several new, results on charging of dust grains of various materials and sizes. Charging processes of dust in space and their influence on the dust dynamics are analyzed in laboratory simulations of secondary emission, field ion and electron emissions, and dust sputtering. Single micrometre-sized grains and grain clusters are stored in a hyperbolic quadrupole field under ultra-high vacuum conditions for long time periods. The charge state of the grain and its evolution are recorded while the grain is exposed to ion or electron beams of various energies and fluxes. The influence of the secondary electron emission on the charge state is measured and compared with a computer model. Limitations on the grain charge by the field electron and ion emission are considered next. The measurements allow analyzing field emission from conductive and dielectric grains. The existence of long-lived surface states on insulating materials, which are probably responsible for the anomalous behavior of field electron emission and the low threshold of the field ion emission, is indicated. The observation of sputtering by energetic ions showing a surprising anisotropic erosion of a conductive grain is analyzed. The sputtering and the field ion emission are discussed as possible sources of the so-called pick-up ions.

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“…Following models designed for scanning electron microscopy (e.g., Li et al 2008;Hovington et al 1997aHovington et al , 1997b, we have developed a numerical model of secondary emission from spherical objects suitable for various materials including metals (Richterová et al 2006a), insulators (Richterová et al 2007;Němeček et al 2011), and complex compounds (Richterová et al 2006b;Mann et al 2011). These papers give many examples of excellent agreement of model results with laboratory measurements on spherical samples; the deviations are of the order of single units percent.…”

Section: Introductionmentioning

confidence: 99%

Secondary Emission From Non-Spherical Dust Grains With Rough Surfaces: Application to Lunar Dust

Richterová

Němeček

Beránek

et al. 2012

ApJ

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Electrons impinging on a target can release secondary electrons and/or they can be scattered out of the target. It is well established that the number of escaping electrons per primary electron depends on the target composition and dimensions, the energy, and incidence angle of the primary electrons, but there are suggestions that the target's shape and surface roughness also influence the secondary emission. We present a further modification of the model of secondary electron emission from dust grains which is applied to non-spherical grains and grains with defined surface roughness. It is shown that the non-spherical grains give rise to a larger secondary electron yield, whereas the surface roughness leads to a decrease in the yield. Moreover, these effects can be distinguished: the shape effect is prominent for high primary energies, whereas the surface roughness predominantly affects the yield at the low-energy range. The calculations use the Lunar Highlands Type NU-LHT-2M simulant as a grain material and the results are compared with previously published laboratory and in situ measurements.

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Secondary emission from dust grains with a surface layer: comparison between experimental and model results

Cited by 6 publications

References 10 publications

Dust Charging in Space‐related Laboratory Experiments: A Review Focused on Secondary Emission

Dust Charging in Space‐related Laboratory Experiments: A Review Focused on Secondary Emission

Interaction between single dust grains and ions or electrons: laboratory measurements and their consequences for the dust dynamics

Secondary Emission From Non-Spherical Dust Grains With Rough Surfaces: Application to Lunar Dust

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