A new fit to secondary emission yield in the low impact voltage regime: An improvement of Vaughan’s expression

First-principles calculations coupled with Monte Carlo simulations are used to probe the role of a surface CO monolayer formation on secondary electron emission (SEE) from Cu, Ag, and Au (110) materials. It is shown that formation of such a layer increases the secondary electron emission in all systems. Analysis of calculated total density of states (TDOS) in Cu, Ag, and Au, and partial density of states (PDOS) of C and O confirm the formation of a covalent type bonding between C and O atoms. It is shown that such a bond modifies the TDOS and extended it to lower energies, which is then responsible for an increase in the probability density of secondary electron generation. Furthermore, a reduction in inelastic mean free path is predicted for all systems. Our predicted results for the secondary electron yield (SEY) compare very favorably with experimental data in all three materials, and exhibit increases in SEY. This is seen to occur despite increases in the work function for Cu, Ag, and Au. The present analysis can be extended to other absorbates and gas atoms at the surface, and such analyses will be present elsewhere.

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Carbon-oxygen surface formation enhances secondary electron yield in Cu, Ag and Au

Brown

Díaz

Aslan

et al. 2022

Sci Rep

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Numerical analysis for suppression of charge growth using nested grooves in rectangular waveguides

Brown

Milestone

Joshi

2022

Journal of Applied Physics

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Multipactor mitigation is of relevance to microwave applications, and external magnetic fields, surface modifications, and materials engineering have previously been utilized for this purpose. In this contribution, geometric modifications made to rectangular waveguide surfaces in the form of nested grooves are investigated for the suppression of multipactor growth. A time-dependent kinetic scheme is used to simulate electron dynamics that folds in electron trapping at the nested groove structures, with inclusion of the electric field perturbations arising from the presence of various grooved geometries. The charge growth in the system is modeled based on an empirical approach that includes both energy and angular dependencies of secondary electron emission from all the different surfaces. A varying number of grooves, their widths, and their placement (either one sided or dual-sided) within the rectangular waveguide structure are included for a more complete analysis. The results demonstrate that nested grooves can lead to reductions in charge growth by over a factor of 280 when compared with a simple waveguide over the same time period. Furthermore, wider nested grooves are shown to have an advantage, with multiple aligned grooves across two parallel surfaces being especially useful at high external fields. Determining optimal combinations for an arbitrary field, operating frequency, and physical dimensions would require further work.

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Empirical modeling and Monte Carlo simulation of secondary electron yield reduction of laser drilled microporous gold surfaces

Iqbal

Ludwick

Fairchild

et al. 2019

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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This work investigates secondary electron yield (SEY) mitigation from a metal surface with a microporous array fabricated using the laser drilling technique. We propose a general empirical model to fit the experimentally measured SEY of a flat gold surface for normal and oblique incidences of primary electrons. Using this empirical model, we develop a two-dimensional Monte Carlo (MC) simulation scheme to determine the effective SEY of a microporous array. It is found that the SEY from a porous surface is significantly reduced compared to that of the flat surface. By taking into account all the generations of secondary electrons inside a well, our MC results are found to be in very good agreement with the experimental data. The dependence of the SEY on the aspect ratio of the micropores and porosity of the surface is examined. A simple empirical formula has been proposed to evaluate the effective SEY of the gold microporous array for pores of arbitrary aspect ratios.

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A new fit to secondary emission yield in the low impact voltage regime: An improvement of Vaughan’s expression

Cited by 3 publications

References 19 publications

Carbon-oxygen surface formation enhances secondary electron yield in Cu, Ag and Au

Carbon-oxygen surface formation enhances secondary electron yield in Cu, Ag and Au

Numerical analysis for suppression of charge growth using nested grooves in rectangular waveguides

Empirical modeling and Monte Carlo simulation of secondary electron yield reduction of laser drilled microporous gold surfaces

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