Modeling of reduced secondary electron emission yield from a foam or fuzz surface

Swanson, Charles; Kaganovich, Igor

doi:10.1063/1.5008261

Cited by 35 publications

(18 citation statements)

References 16 publications

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“…In this way, it is possible to achieve extremely low SEYs even for high primary energies 21 , which is highly desirable for a wide range of technological applications. Other studies in the literature report low SEY of high aspect ratio surfaces 9–11,22–24 . In the present study we find even lower SEY values for much lower aspect ratios due to the electric field between the metal and dielectric domains of the coating.…”

Section: Introductionmentioning

confidence: 83%

Dynamic secondary electron emission in rough composite materials

Olano

Dávila

Dennison

et al. 2019

Sci Rep

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The interaction of ionizing radiation with matter is of critical importance in numerous areas of science and technology like space and vacuum technology and even medicine and biotechnology. Secondary electron emission is a consequence of electron irradiation on materials. We achieve extremely low secondary electron emission yield values smaller than 0.2, even up to incident electron energies ~1 keV, due to an undocumented synergy between neighbouring metal and dielectric domains in composite samples. To investigate this experimental discovery, we propose a simple 3D model where the dielectric and metallic domains are arranged in parallel and interleaved. The proposed surface profile has a triangular shape to model the surface roughness. We obtain a continuous equation to describe the electric field that arises between grounded conductors and charged dielectrics domains. The calculated trajectories of secondary electrons in this 3D geometry are used to predict dynamic secondary emission yield, which strongly depends on the charge accumulated in the dielectric domains. This research paves the way to design new materials of low secondary emission yield, addressing the technological problem not yet resolved to inhibit the electron avalanche in RF equipment that limit their maximum working power.

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Section: Introductionmentioning

confidence: 83%

Dynamic secondary electron emission in rough composite materials

Olano

Dávila

Dennison

et al. 2019

Sci Rep

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“…Since the SEE yield is relatively flat above 200 eV, 3,5,9 it may be assumed that a nearly 35% reduction in SEE also occurs for 500 eV incident electrons. Analytical 10 and Monte Carlo [8][9][10]15,16 modeling of fibrous surfaces have confirmed that the reduction in SEE is due to trapping of emitted electrons (mostly true secondary electrons with a cosine angular distribution), especially for high aspect-ratio fibers.…”

mentioning

confidence: 84%

“…Many recent experimental and modeling efforts have investigated textured materials to reduce SEE. These include metallic surfaces with nm to mm-sized vertical fibers/velvet, 5,[8][9][10][11][12][13][14][15] isotropically aligned fibers/fuzz, 3,8,9,16 pores, 17,18 triangular and rectangular grooves, [19][20][21] soot particles, 22 and surface roughness. 23 For example, in a previous publication, we found that the SEE yield was reduced by more than 40% for tungsten fuzz generated in helium plasma under tokamak-like conditions when compared to smooth tungsten.…”

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confidence: 99%

Electron emission from carbon velvet due to incident xenon ions

Patino

Wirz

2018

Applied Physics Letters

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We present measurements of the ion-induced electron emission from carbon velvet. The results from carbon velvet with high aspect ratio vertical fibers (6.8 lm diameter and 2.6 mm length) show a more than 60% reduction in ion-induced electron emission for normal incident xenon ions over the entire ion incident energy investigated (i.e., 500-2000 eV) when compared to graphite. This is important for plasma-facing surfaces that are exposed to large fluxes of energetic ions, such as beam dumps and chamber walls used to control facility effects in plasma-thruster ground tests.

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“…The whole volume porosity is 60 ± 5%. The complex structure of a foam should reduce secondary electron emission and prevent ion rebounds [50][51][52][53][54]. The active length of the stainless steel cup is 50 mm (l cup ).…”

Section: Architecturementioning

confidence: 99%

Optimization of a Faraday Cup Collimator for Electric Propulsion Device Beam Study: Case of a Hall Thruster

Hugonnaud

Mazouffre

2021

Applied Sciences

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A Faraday cup (FC) is an instrument dedicated to current measurement in beams, jets and plasmas. It consists of a set of polarized electrodes mounted in such a way plasma sheath effect can be neglected, yielding accurate and reliable results. A FC is composed of three main parts, namely a collector or cup, which collects the current, a collimator, which defines the collection area and can contribute to limit electrons from entering the cup and a housing which protects the instrument from perturbation caused by the surrounding medium. In this paper, we provide experimental results of the effect of the collimator upon the measured ion current within the beam of a low-power Hall thruster. Different collimator materials, aperture diameters and polarization voltages are studied to determine the optimum design. Minimum dimension as well as appropriate materials are given as a conclusion in the case of low-power Hall thruster beam investigation.

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Modeling of reduced secondary electron emission yield from a foam or fuzz surface

Cited by 35 publications

References 16 publications

Dynamic secondary electron emission in rough composite materials

Dynamic secondary electron emission in rough composite materials

Electron emission from carbon velvet due to incident xenon ions

Optimization of a Faraday Cup Collimator for Electric Propulsion Device Beam Study: Case of a Hall Thruster

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