CuO nanowires for inhibiting secondary electron emission

Aguilera, Lydya; Montero, I.; Dávila, M. E.; Ruiz, A.; Galán, L.; Nistor, V.; Raboso, D.; Palomares, F. J.; Soria, F.

doi:10.1088/0022-3727/46/16/165104

Cited by 45 publications

(28 citation statements)

References 16 publications

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“…The observed XPS proved to contradict the known reduction of AMP outlined above [27][28][29]37]. We suspect this is due to secondary electrons [39] generated in the experimental procedure effecting reduction of the virgin samples to a greater extent than the irradiated ones. EPR of Mo V centres generated a distinctive signal (g = 2.7737) corresponding to previous literature references [29,40], which increased in intensity with the redshift of the samples explored, as per Figures 4 and 5.…”

Section: Chemical Changes Induced In Amp Upon Irradiationmentioning

confidence: 74%

The Effect of Gamma Irradiation on the Physiochemical Properties of Caesium-Selective Ammonium Phosphomolybdate–Polyacrylonitrile (AMP–PAN) Composites

et al. 2019

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Managing certain by-products of the nuclear fuel cycle, such as the radioactive isotopes of caesium: 134Cs, 135Cs and 137Cs is challenging due to their environmental mobility and radioactivity. While a great many materials can isolate Cs+ ions from neutral or basic aqueous solutions via ion exchange, few of these, with the exception of ammonium phosphomolybdate (AMP), function effectively in acidic media. The use of AMP, and its porous composite in polyacrylonitrile (PAN) for management of Cs radioisotopes in various nuclear wastes have been known for decades and are well studied, yet the effects of radiation on the physiochemical properties of such composites have only received limited attention to date. In a previous publication, we demonstrated that a 100 kGy gamma irradiation dose has negligible effect on the ion exchange performance of AMP and AMP–PAN with respect to capacity or kinetics under the Cs+ concentrations and acidity found in spent nuclear fuel (SNF) recycling. As a continuation of this prior study, in this publication we explore the effects of gamma irradiation on the physiochemical properties of AMP and AMP–PAN using a range of characterisation methods. The effects of the same gamma dose on the oxidation state of Mo in AMP and AMP–PAN, the thermal degradation of both AMP and AMP–PAN, combined with a first study into the high-temperature degradation AMP, are reported. The implications of irradiation, its possible mechanism, the conditions present in SNF recycling, and for the end-of-life disposal or recycling of these materials are also discussed.

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Section: Chemical Changes Induced In Amp Upon Irradiationmentioning

confidence: 74%

The Effect of Gamma Irradiation on the Physiochemical Properties of Caesium-Selective Ammonium Phosphomolybdate–Polyacrylonitrile (AMP–PAN) Composites

et al. 2019

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“…Thus, understanding how SEE affects sheath stability is crucial to make predictions of channel wall lifetime.Recently, a new wall concept based nano-architected surfaces has been proposed to mitigate surface erosion and SEE [22][23][24][25]. Demonstration designs based on high-Z refractory materials have been developed, including architectures based on metal nanowires and nanofoams [26][27][28][29][30]. The idea behind these designs is to take advantage of very-high surface-to-volume ratios to reduce SEE and ion erosion by internal trapping and redeposition.…”

mentioning

confidence: 99%

“…< R ≤ P el =⇒ elastic scattering P el < R ≤ P el + P p =⇒ plasmon excitation P el + P p < R ≤ P el + P p + P c =⇒ conduction electron excitation P el + P p + P c < R ≤ 1 ≡ P el + P p + P c + P s =⇒ inner shell electron excitation(28) …”

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confidence: 99%

Calculation of secondary electron emission yields from low-energy electron deposition in tungsten surfaces

Chang

Alvarado

Marian

2018

Applied Surface Science

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We present calculations of secondary electron emission (SEE) yields in tungsten as a function of primary electron energies between 50 eV and 1 keV and incidence angles between 0 and 90 • . We conduct a review of the established Monte Carlo methods to simulate multiple electron scattering in solids and select the best suited to study SEE in high-Z metals. We generate secondary electron yield and emission energy functions of the incident energy and angle and fit them to bivariate fitting functions using symbolic regression. We compare the numerical results with experimental data, with good agreement found. Our calculations are the first step towards studying SEE in nanoarchitected surfaces for electric propulsion chamber walls. IntroductionSecondary electron emission (SEE) is the emission of free electrons from a solid surface, which occurs when these surfaces are irradiated with external (also known as primary) electrons. SEE is an important process in surface physics with applications in numerous fields, such as electric propulsion [1-5], particle accelerators [6], plasma-walls in fusion reactors [7][8][9][10][11], electron microscopy and spectroscopy [12,13], radio frequency devices [14-16], etc. In Hall thrusters for electric propulsion, a key component is the channel wall lining protecting the magnetic circuits from the discharge plasma. These channel walls are a significant factor in Hall thruster performance and lifetime through its interactions with the discharge plasma. These interactions are governed by the sheath formed along the walls, and so the properties of the sheath determine the amount of electron energy absorbed by the wall, which in turn affects the electron dynamics within the bulk discharge [1,[17][18][19]. Furthermore, the energy imparted by the sheath to the ions within the discharge determines the impact energy and incident angle of ions upon the surface, thus affecting the amount of material sputtered and consequently the wall erosion rate [20,21]. Thus, understanding how SEE affects sheath stability is crucial to make predictions of channel wall lifetime.Recently, a new wall concept based nano-architected surfaces has been proposed to mitigate surface erosion and SEE [22][23][24][25]. Demonstration designs based on high-Z refractory materials have been developed, including architectures based on metal nanowires and nanofoams [26][27][28][29][30]. The idea behind these designs is to take advantage of very-high surface-to-volume ratios to reduce SEE and ion erosion by internal trapping and redeposition. Preliminary designs are based on W, W/Mo, and W/Re structures, known to have intrinsically low sputtering yields secondary

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“…Second, the surface asperities can act as traps for emitted electrons that can be re-captured by the solid 14 . These shadowing effects are dominant in materials with high roughness 15 . Some authors [15][16][17] have worked on lowering the EEY by creating surface asperities chemically 15 , mechanically 16 or using laser engraving 17 .…”

mentioning

confidence: 99%

Effect of rectangular grooves and checkerboard patterns on the electron emission yield

Pierron

Inguimbert

Belhaj

et al. 2018

Journal of Applied Physics

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The effect of rough structures on the electron emission under electron impact between 10 eV and 2 keV is investigated with a new version of the low energy electromagnetic model of GEANT4 (MicroElec). The inelastic scattering, is modeled thanks to the dielectric function theory and the Mott's model of partial waves to describe the elastic scattering. Secondary electron emission is modeled for grooved and checkerboard patterns of different dimensions for aluminum and silver. The analyses is performed according to two shape parameters h/L and d/L, h being the height, L the width of the structures and d the spacing between two neighboring structures. The secondary electron emission is demonstrated to decrease when h/L and d/L ratios increase. When the height reaches 10 times the lateral dimensions, the electron emission yield is divided by two compared to that of a flat sample. The optimization of the two aspects ratios lead to a reduction of the electron emission yield of 80 % for grooved patterns, and of 98 % for checkerboard patterns. This purely geometric effect is similar for aluminum and silver materials. A simple analytical model, capable to reproduce the effect on the electron emission yield of checkerboard and grooved patterns, is proposed. This model is found to be in good agreement with the Monte Carlo simulations and some experimental measurements performed in our irradiation facility.

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CuO nanowires for inhibiting secondary electron emission

Cited by 45 publications

References 16 publications

The Effect of Gamma Irradiation on the Physiochemical Properties of Caesium-Selective Ammonium Phosphomolybdate–Polyacrylonitrile (AMP–PAN) Composites

The Effect of Gamma Irradiation on the Physiochemical Properties of Caesium-Selective Ammonium Phosphomolybdate–Polyacrylonitrile (AMP–PAN) Composites

Calculation of secondary electron emission yields from low-energy electron deposition in tungsten surfaces

Effect of rectangular grooves and checkerboard patterns on the electron emission yield

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