Dynamic secondary electron emission in rough composite materials

Olano, Leandro; Dávila, M. E.; Dennison, John; Martín-Iglesias, Petronilo; Montero, I.

doi:10.1038/s41598-019-50353-3

Cited by 8 publications

(5 citation statements)

References 28 publications

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“…As a result, more electrons are able to overcome the work function barrier, and they are ejected as SEs despite the larger work function of an oxide compared to a metal. On top of this, the sandblasted (+ nanoparticle catalytic coating) surface should show a lower SE emission coefficient than the blank surface, because emitted electrons are re-trapped by surface irregularities [64].…”

Section: Ammonia Synthesis In He Diluted Rf Plasmasmentioning

confidence: 99%

Ammonia synthesis by plasma catalysis in an atmospheric RF helium plasma

Vervloedt,

von Keudell

2024

Plasma Sources Sci. Technol.

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The in-plasma-catalytic synthesis of ammonia from nitrogen and hydrogen admixed to a helium RF plasma is studied with infrared absorption spectroscopy, optical emission spectroscopy, and through chemical kinetics modeling. Sandblasted glass is used as support for iron, platinum, and copper catalysts up to a surface temperature of 150 ○C. It is shown that the optimum ammonia production occurs at very small N2/(N2+H2) ratios with an increase of concentration with plasma power. The global kinetic modelling agrees well with the data for a variation of the N2+H2 admixture and the absorbed plasma power. The introduction of the catalyst enhances ammonia production by up to a factor of 2. Based on the comparison with the modelling, this is linked to a change in the electron kinetics due to the presence of the catalyst. It is postulated that introducing the catalyst increases the reduced electric field, because it reduces the secondary electron emission coefficient. As a result, the dissociation of N2 is stimulated, thereby enhancing the NH3 formation. These experiments show that the impact of the catalyst on the plasma performance in noble gas-diluted RF plasmas can be more important than the impact of the plasma on any catalytic surface process.

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Section: Ammonia Synthesis In He Diluted Rf Plasmasmentioning

confidence: 99%

Ammonia synthesis by plasma catalysis in an atmospheric RF helium plasma

Vervloedt,

von Keudell

2024

Plasma Sources Sci. Technol.

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“…Instead, these seem to be epoxy resin arising from sample preparation, charging under the electron irradiation. 37 However, it is not clear whether these gaps are process related or originated due to metallurgical preparation. Highlighted area on the left side shows the critical spot below the nub.…”

Section: Joint Formation and Microstructural Featuresmentioning

confidence: 99%

Feasibility study of friction stir joining of aluminium with carbon fibre reinforced thermoplastic composite

Malaske,

Blaga,

Bergmann

et al. 2024

Journal of Composite Materials

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During the last decades, environmental concerns and limited resources have set focus of research on lightweight, mechanically high-performing structures for the transportation industry, in order to reduce fuel consumptions and CO2 emissions. Friction Stir Joining (FSJ), as a variant of the Friction Stir Welding (FSW), is an innovative friction-based joining technique for metal-composite hybrid structures. Joining in the plasticized state below the melting temperature of the metal leads to a comparatively small heat-affected zone, so that only minor metallurgical changes occur. Additionally, only a short processing time and no additional weight in form of fasteners is needed. The main objective of this study is to evaluate the feasibility of metal-composite structures via FSJ, intending to enable a macro-mechanical interlocking bonding mechanism. Main focus was given to the integration of an aluminium nub inserted in a carbon fiber-reinforced polyphenylene sulfide (CF-PPS) sheet, to ensure sufficient plasticization of the aluminium part and no degradation in the polymer part. Residual stress arising from the friction stir joining process was also characterised using the Contour method. In this study, aluminium alloy 6082-T6 and CF-PPS composite sheets were used to produce long lap joints. Results have shown that the joints were created at almost constant peak temperature slightly above the melting temperature of the PPS but no physical-chemical changes were detected in the PPS. In addition, the influence of a PPS film as interlayer between the sheets was investigated in order to explore a method for preventing galvanic corrosion. Preliminary results indicate that it is not possible to integrate a metal nub to the CF-PPS without interrupting the PPS film. However, it is possible to create a nub within the PPS film.

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“…Although this effect is typically not considered in spacecraft charging codes, it is important to recognize that it may well occur in materials studies measuring yields from bulk insulators, nonconductive coatings, or biased samples as these materials are most likely to retain charge (Hoffmann & Dennison, 2012). Olano et al (2019) describes an interesting system where surface roughness and charging effects of conductor/dielectric composites are evident.…”

Section: Selecting Materials and Specific Data Based On Mission Speci...mentioning

confidence: 99%

Strategies for Determining Electron Yield Material Parameters for Spacecraft Charge Modeling

Lundgreen

Dennison

2020

Space Weather

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Accurate modeling of spacecraft charging is essential to mitigate well-known and all-too-common deleterious and costly effects on spacecraft resulting from charging induced by interactions with the space plasma environment. This paper addresses how limited availability of electron emission and transport properties of spacecraft materials-in particular, secondary electron yields-and the wide ranges measured for such properties pose a critical issue for modeling spacecraft charging. It describes a materials charging database for electron emission properties under development, which facilitates more accurate spacecraft charge modeling when used in concert with the strategies outlined herein. These data and techniques provide tools for more accurate material selection, increased confidence in charge models, and a concomitant decrease in mission risk. They also allow better customization of models in response to prolonged space environment exposure and specific mission requirements, which may evolve materials properties.

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Dynamic secondary electron emission in rough composite materials

Cited by 8 publications

References 28 publications

Ammonia synthesis by plasma catalysis in an atmospheric RF helium plasma

Ammonia synthesis by plasma catalysis in an atmospheric RF helium plasma

Feasibility study of friction stir joining of aluminium with carbon fibre reinforced thermoplastic composite

Strategies for Determining Electron Yield Material Parameters for Spacecraft Charge Modeling

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