Low energy electron reflection from tungsten surfaces

Tolias, Panagiotis

doi:10.48550/arxiv.1601.02047

Cited by 8 publications

(13 citation statements)

References 40 publications

(55 reference statements)

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“…The scattering of valence electrons is a many-body problem and hence more challenging to model; however, some authors have introduced an imaginary part to the potential barrier to describe the inelastic aspects. [51,52] We refer the reader to Reference [53] for a concise discussion on the topic.…”

Section: Discussionmentioning

confidence: 99%

Plasmonic effects in the neutralization of slow ions at a metallic surface

Bercx,

Mayda,

Depla

et al. 2023

Contributions to Plasma Physics

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Secondary electron emission is an important process that plays a significant role in several plasma‐related applications. As measuring the secondary electron yield experimentally is very challenging, quantitative modelling of this process to obtain reliable yield data is critical as input for higher‐scale simulations. Here, we build upon our previous work combining density functional theory calculations with a model originally developed by Hagstrum to extend its application to metallic surfaces. As plasmonic effects play a much more important role in the secondary electron emission mechanism for metals, we introduce an approach based on Poisson point processes to include both surface and bulk plasmon excitations to the process. The resulting model is able to reproduce the yield spectra of several available experimental results quite well but requires the introduction of global fitting parameters, which describe the strength of the plasmon interactions. Finally, we use an in‐house developed workflow to calculate the electron yield for a list of elemental surfaces spanning the periodic table to produce an extensive data set for the community and compare our results with more simplified approaches from the literature.

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Section: Discussionmentioning

confidence: 99%

Plasmonic effects in the neutralization of slow ions at a metallic surface

Bercx,

Mayda,

Depla

et al. 2023

Contributions to Plasma Physics

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“…A lot of semi-empirical models have been carried out to describe the SEE. [3,[13][14]19] By using the Equation ( 1), I es based on S-formula for the q-distribution electrons can be expressed as. [6,9] I es = en e 𝜋r…”

Section: Theoretical Modelmentioning

confidence: 99%

“…The coefficients of P 1,e , W 1 , P, R e,∞ , E r , and r in Equations ( 15) and ( 16) are determined by fitting the experimental dates. For the polycrystalline tungsten, 𝜂 e and R e have been collated and organized in Reference [14] in the incident energy range 0 − 30 eV from the experiments of Bronstein et al [20] Based on the existing experimental data results shown in Reference [14], we can obtain the profiles of the 𝜂 e and R e for the F-P model by using the curve fitting. By the optimized F-P model parameters in Equations ( 15) and ( 16), the fitting functions of 𝜂 e and R e are obtained for the minimum of the sum of squares due to error (SSE):…”

Section: Theoretical Modelmentioning

confidence: 99%

“…Usually, the electrons re-emerge due to the SEE involving backscattered electrons emission (BEE), inelastic reflection emission (IRE) and TEE. [13,14] In some plasma fields such as in tokamak edge, the contribution of the SEE current to the tungsten (W) dust particle may be obviously underestimated if the BEE and IRE is not taken into account for the plasma with the energy range 5 < T e < 50 eV. [14] Since the SEE including the BEE, IRE and TEE plays an important role on the dust particle potential and then modifies the dust particle lifetime, it is necessary to investigate the impact of SEE on the dust particle in a plasma with super-extensive electrons, because the presence of the super-extensive electrons can have enough energy and then eject the secondary electrons from a dust particle producing a SEE current.…”

Section: Introductionmentioning

confidence: 99%

“…[13,14] In some plasma fields such as in tokamak edge, the contribution of the SEE current to the tungsten (W) dust particle may be obviously underestimated if the BEE and IRE is not taken into account for the plasma with the energy range 5 < T e < 50 eV. [14] Since the SEE including the BEE, IRE and TEE plays an important role on the dust particle potential and then modifies the dust particle lifetime, it is necessary to investigate the impact of SEE on the dust particle in a plasma with super-extensive electrons, because the presence of the super-extensive electrons can have enough energy and then eject the secondary electrons from a dust particle producing a SEE current. [9] In this paper, we examine the dust particle potential modified by the emission of secondary electrons from the dust particle in a plasma with super-extensive electrons, and then investigate the evolution of the dust particle temperature in the dust particle heating process.…”

Section: Introductionmentioning

confidence: 99%

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Secondary electron emission impact on the tungsten dust particle in a plasma with super‐extensive electrons

Long

2023

Contributions to Plasma Physics

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On thermionic emission from plasma-facing components in tokamak-relevant conditions

Komm

Ratynskaia

Tolias

et al. 2017

Plasma Phys. Control. Fusion

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The first results of particle-in-cell simulations of the electrostatic sheath and magnetic pre-sheath of thermionically emitting planar tungsten surfaces in fusion plasmas are presented. Plasma conditions during edge localized modes (ELMs) and during inter-ELM periods have been considered for various inclinations of the magnetic field and for selected surface temperatures. All runs have been performed under two assumptions for the sheath potential drop; fixed or floating. The primary focus lies on the evaluation of the escaping thermionic current and the quantification of the suppression due to the combined effects of space-charge and Larmor gyration. When applicable, the results are compared with the predictions of analytical models. The heat balance in the presence of thermionic emission as well as the contribution of the escaping thermionic current to surface cooling are also investigated. Regimes are identified where emission needs to be considered in the energy budget.

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Low energy electron reflection from tungsten surfaces

Cited by 8 publications

References 40 publications

Plasmonic effects in the neutralization of slow ions at a metallic surface

Plasmonic effects in the neutralization of slow ions at a metallic surface

Secondary electron emission impact on the tungsten dust particle in a plasma with super‐extensive electrons

On thermionic emission from plasma-facing components in tokamak-relevant conditions

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