Secondary electron emission characteristics of graphene films with copper substrate

Wang, Jie; Wang, Yong; Xu, Yanhui; Zhang, Yuxin; Zhang, Bo; Wei, Wei

doi:10.1088/1674-1137/40/11/117003

Cited by 18 publications

(20 citation statements)

References 16 publications

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“…The results obtained are shown in Fig. 2, which also includes experimental data reported by Wang 27 and Xie. 28 The following aspects are evident from the plots: (a) Predictions of the SEY values are generally in good agreement with the measurements for a graphene coated copper substrate.…”

confidence: 54%

“…24,25 More recent studies of energy-dependent SEY for graphene coated copper systems have been reported, and they all point to the benefits of this approach. [26][27][28] However, numerical studies of SEY on graphene coated copper have not been performed, nor have careful comparisons with experimental data been made. The present study represents an effort in this direction.…”

confidence: 99%

“…Thus it remains unclear why the modest shifts might cause large changes in SEY values from over 1.0 for pure copper, as reported. 22,[26][27][28] Here we focus on the two-dimensional nature of the graphene layers. Transmission of secondary electrons incident on the metal-graphene interface from the metal would conserve momentum along the parallel direction during their transit.…”

confidence: 99%

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Calculations of secondary electron yield of graphene coated copper for vacuum electronic applications

et al. 2018

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The suppression of secondary electron yield (SEY) which can possibly lead to multipactor is an important goal for several applications. Though some techniques have focused on geometric modifications to lower the SEY, the use of graphene coatings as thin as a few monolayers is a promising new development that deserves attention either as a standalone technique or in concert with geometric alterations. Here we report on Monte Carlo based numerical studies of SEY on graphene coated copper with comparisons to recent experimental data. Our predicted values are generally in good agreement with reported measurements. Suppression of the secondary electron yield by as much as 50 percent (over copper) with graphene coating is predicted at energies below 125 eV, and bodes well for multipactor suppression in radio frequency applications.

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confidence: 54%

confidence: 99%

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Calculations of secondary electron yield of graphene coated copper for vacuum electronic applications

et al. 2018

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“…The electron cloud is a key problem in particle accelerators, which can cause the degradation of beam quality and limit the performance of particle accelerators with high energy, high intensity, high luminosity and long beam lifetime [1][2][3][4][5][6][7][8]. The methods of mitigating electron cloud effect have been studied by many researchers from several organizations, such as CERN [9,10], STFC [11,12], NSRL [13], KEK [7,14], INFN [15], etc. C. Yin Vallgren et al found that a complete suppression of e-cloud can be achieved by amorphous carbon coating of liners [9].…”

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confidence: 99%

The Effect of Air Exposure on SEY and Surface Composition of Laser Treated Copper Applied in Accelerators

Wang

Sian

Valizadeh

et al. 2018

IEEE Trans. Nucl. Sci.

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In this paper, the effect of air exposure and acetone cleaning on the secondary electron yield (SEY) of laser treated copper were investigated and discussed. The SEY of laser treated copper samples after acetone cleaning and air exposure were measured. After 10 to 21 months air exposure, the maximum SEY increased by about 11%~20%. Furthermore, changes of carbon, copper, and oxygen chemistry states from sample surface after acetone and air exposure were studied by means of XPS. The XPS results show that the concentration of Cu decreased by about 61%~70% after acetone cleaning and decreased by a further 36%~70% after 10 to 21 months air exposure. Moreover, the XPS measurement reflects the significant increase of the total percentages of C and O after acetone cleaning, and further increase after 10 to 21 months air exposure. The increase of SEY is explained in terms of the introduction of impurities, such as oxide, carbide etc.

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“…Titanium nitride, chromium nitride and carbon nitride are typical candidates [20]. The effect of thickness, elemental content and geometric morphology of the novel coatings on reducing SEY have been investigated [21,22]. Based on the measured SEY, numerical simulation is employed to calculate multipactor threshold and to ensure the effectiveness and feasibility of proposed treatment approaches for microwave power components [23,24].…”

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confidence: 99%

Significantly Reduced Secondary-Electron-Yield of Aluminum Sheet with Fluorocarbon Coating

Wang

Zhao

et al. 2018

Coatings

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In this work, the surface of Al sheet was coated with a fluorocarbon (FC) thin film by radio frequency (RF) sputtering of polytetrafluoroethylene (PTFE) to investigate the influence of dielectric coatings on the secondary electron yield (SEY) behavior of Al sheets. Atomic-force microscopy (AFM) and energy-dispersive spectroscopy (EDS) were employed to identify the surface topographies and elemental contents of the samples with FC coatings. Water contact angle (WCA) measurements were performed to characterize the surface tension as well as the polar and dispersion components of the samples' surface. The secondary electron-mission (SEE) behavior of the samples was determined by measuring the SEY coefficients in an ultra-high vacuum chamber with three electron guns. The experimental results indicated that the longer sputtering time effectively led to the increase in coating thickness and a higher ratio of F/C, as well as the continued decrease of surface tension. A quite thin FC coating of about 11.3 nm on Al sheet resulted in the value of maximum SEY (δ max ) dropping from 3.02 to 1.85. The further increase in coating thickness beneficially decreased δ max down to 1.60, however, at the cost of a ten-fold thicker coating (ca. 113 nm). It is found that increasing the coating thickness contributes to reducing SEY coefficients as well as suppressing SEE. The results are expected to guide the design of dielectric-coating for SEY reduction as well as multipactor suppression on Al.2 of 12 of a sample surface can be tailored to create triangular, rectangular and micro-porous grooves through several approaches such as laser lithography and laser and chemical etching. Parts of the primary incident electrons are trapped in the grooved structures by changing its trajectory, thus restraining SEE [9][10][11][12]. On the premise of a large depth-to-width ratio and high aspect ratio, rough surfaces with irregular structures created by artificial means also work. The surface roughness is likely to act as a blackbody or rough surface cage. Particle bombardment is an emerging and promising method to prepare rough surfaces with reduced SEY. Yang et al. [13] found that argon ion sputtering reduced the SEY of gold by eliminating contamination but also the roughing surface induced ion bombardment. An "equivalent work-function" relating the effect of contamination and surface roughness was proposed to predict SEY. Furthermore, Hu et al. [14] analyzed the influence of bombardment intensity and ion energy on the SEY of copper plates. Based on different surface topographies fabricated by ion bombardment, the optimized ion-beam parameters to achieve the lowest SEY of copper were obtained. In association with the experimental construction of rough structures, numerical simulation and dynamic calculation have developed rapidly. Theoretical research has mainly focused on building up rough-structure models, which consider the energy and incident angle of primary electrons. Chang et al. [15] applied particle-in-cell simulation to analyze the chang...

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Secondary electron emission characteristics of graphene films with copper substrate

Abstract: Secondary electron emission characteristics of graphene films with copper substrate * Jie Wang( ) Yong Wang( ) 1) Yanhui Xu( ) Yuxin Zhang( ) Bo Zhang( ) 2) Wei Wei( )

Cited by 18 publications

References 16 publications

Calculations of secondary electron yield of graphene coated copper for vacuum electronic applications

Calculations of secondary electron yield of graphene coated copper for vacuum electronic applications

The Effect of Air Exposure on SEY and Surface Composition of Laser Treated Copper Applied in Accelerators

Significantly Reduced Secondary-Electron-Yield of Aluminum Sheet with Fluorocarbon Coating

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