Role of surface microgeometries on electron escape probability and secondary electron yield of metal surfaces

Bajek, David; Wackerow, Stefan; Zanin, D.; Baudin, Lucie; Bogdanowicz, Karolina; Valdivieso, E. Garcia Tabares; Calatroni, S.; Girolamo, B. Di; Sitko, M.; Himmerlich, Marcel; Taborelli, M.; Chiggiato, Paolo; Abdolvand, Amin

doi:10.1038/s41598-019-57160-w

Cited by 24 publications

(20 citation statements)

References 20 publications

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“…The estimated ablation threshold of 0.13 W corresponds to a laser fluence threshold of ~0.4 J/cm 2 . The value is of the same order of magnitude as the published value for 532 nm, which is ~0.24 J/cm 2 [2].…”

Section: Characterization Of the Laser Ablationsupporting

confidence: 78%

“…A hybrid simulation, that couples the finite difference method to solve the heat transfer equations with molecular dynamics calculations, allows a good description of the ablation mechanism [27]. The ablation process of metal surfaces results, in addition to ablation pits, for suitable laser parameters in the formation of a nanostructured surface [31] with interesting and adjustable physical quantities, such as low reflectivity [31] and low secondary electron yield (SEY) [2, 7, 8, 14, 32, 34-37, 39, 40] enabling multiple applications [2,11,12,39]. SEY is the physical quantity which governs multipacting in radiofrequency devices, charging phenomena in satellites and electron cloud in particle accelerators.…”

Section: Introductionmentioning

confidence: 99%

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Secondary electron yield reduction of copper after 355 nm ultrashort pulse laser ablation

Lorenz

Himmerlich

Ehrhardt

et al. 2022

Lasers Manuf. Mater. Process.

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Nanostructured surfaces exhibit remarkable chemical, physical and microbiological properties and have therefore various technical and industrial applications. The ultrashort laser pulse irradiation (wavelength λ = 355 nm, pulse duration Δtp = 12 ps, repetition rate f = 100 kHz) of copper samples with appropriate laser parameters results in the formation of a micro- and nanostructured surfaces. The influence of these hierarchically textured surfaces on the secondary electron yield (SEY) was studied especially with regard to their morphological and geometrical properties. Specific SEY changes are caused by both, the shape and the depth of the microstructures, as well as the morphology of the formed nanostructures; that can be either compact flower head-like nanostructures, non-compact filament-shaped nanostructures, molten and resolidified spherical structures, or minor modified surfaces. The measured SEY as a function of the primary electron energy is correlated with the surface topography that forms upon laser irradiation. The SEY decreases with increasing accumulated laser fluence and ablated volume, respectively. Especially flower-head-like nanostructures can be produced at high laser power (P ≥ 400 mW) and low scanning velocity (v ≤ 10 mm/s) and represent a surface with strongly reduced SEY maximum as low as 0.7.

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Section: Characterization Of the Laser Ablationsupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Secondary electron yield reduction of copper after 355 nm ultrashort pulse laser ablation

Lorenz

Himmerlich

Ehrhardt

et al. 2022

Lasers Manuf. Mater. Process.

View full text Add to dashboard Cite

show abstract

“…The roughness of a fuzz surface is not manageable by the user when it is produced inside a fusion reactor. In contrast, a featured surface allows controlling the SEY by adjusting the shape and the aspect ratio of the pattern [22][23][24] . The pattern can be regular, as in the case of continuously shaped surfaces with different groove profiles 22,23 , or irregular, as in the case of velvet surfaces (lattices of normally-oriented fibers) 24 .…”

Section: Openmentioning

confidence: 99%

Secondary electron emission under magnetic constraint: from Monte Carlo simulations to analytical solution

Costin

2021

Sci Rep

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The secondary electron emission process is essential for the optimal operation of a wide range of applications, including fusion reactors, high-energy accelerators, or spacecraft. The process can be influenced and controlled by the use of a magnetic field. An analytical solution is proposed to describe the secondary electron emission process in an oblique magnetic field. It was derived from Monte Carlo simulations. The analytical formula captures the influence of the magnetic field magnitude and tilt, electron emission energy, electron reflection on the surface, and electric field intensity on the secondary emission process. The last two parameters increase the effective emission while the others act the opposite. The electric field effect is equivalent to a reduction of the magnetic field tilt. A very good agreement is shown between the analytical and numerical results for a wide range of parameters. The analytical solution is a convenient tool for the theoretical study and design of magnetically assisted applications, providing realistic input for subsequent simulations.

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“…Laser ablation is a novel way to produce a low-SEY surface, first proposed by Reza in 2014, to suppress the secondary electron emission in accelerators [ 23 , 24 , 25 ]. The secondary electrons emitted inside the porous structure are more likely to be trapped during collisions with the porous surface walls, resulting in a decrease in SEY.…”

Section: Introductionmentioning

confidence: 99%

Structural and Secondary Electron Yield Properties of Titanium–Palladium Films with Laser-Treated Copper Substrate for Application in Neutron Generators

Gao

Wang

et al. 2021

Materials

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Secondary electron emission (SEE) of the oxygen-free high-conductivity copper (OFHC) target surface in neutron generators limits the stability and improvement of the neutron yield. A novel-type target of titanium–palladium films coated on laser-treated OFHC target substrate was proposed and explored in this work to obtain low secondary electron yield (SEY) without introducing any components. The combination of Ti–Pd films and laser-treated OFHC substrate can effectively suppress secondary electron emission and enhance the adsorption ability to hydrogen isotopes with the existence of Pd film. The surface morphologies, surface chemical states, and SEYs of Ti–Pd films with laser-treated OFHC substrate were studied systematically for the first time. The XPS results showed that the laser-treated OFHC substrate surface was basically covered by Pd film. However, the Pd film surface was partially oxidized, with percentages of 21.31 and 10.02% for PdO and PdO2, respectively. The SEYs of Ti–Pd films with laser-treated OFHC substrate were all below 1 within the investigated primary energy range of 100–3000 eV, which would be sufficient for application in neutron generators. Specifically, the maximum SEY (δmax) of laser-treated OFHC substrate coated by Ti–Pd films was 0.87 with corresponding incident electron energy of 400 eV.

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Role of surface microgeometries on electron escape probability and secondary electron yield of metal surfaces

Cited by 24 publications

References 20 publications

Secondary electron yield reduction of copper after 355 nm ultrashort pulse laser ablation

Secondary electron yield reduction of copper after 355 nm ultrashort pulse laser ablation

Secondary electron emission under magnetic constraint: from Monte Carlo simulations to analytical solution

Structural and Secondary Electron Yield Properties of Titanium–Palladium Films with Laser-Treated Copper Substrate for Application in Neutron Generators

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