The Effect of Ultrasonic Cleaning on the Secondary Electron Yield, Surface Topography, and Surface Chemistry of Laser Treated Aluminum Alloy

Laser ablation technique is a novel method for obtaining a surface with a low secondary electron yield (SEY) that can mitigate electron cloud in high-energy accelerators. Before the installation of laser processed aluminum alloy, surface cleaning is of the essence to reduce the contaminations of ultra-high vacuum systems for providing appropriate pressure for beam operation consequently. Laser processed aluminum alloy is one of the crucial candidates for the vacuum system construction of future accelerators. Moreover, ultrasonic cleaning is an essential procedure for most materials applied in vacuum systems. Therefore, in order to verify the stability of the laser created structures by ultrasonic cleaning and evaluate the impact of the cleaning on the SEYs, the surface topographies, and the surface chemistries of laser treated aluminum alloy, SEY measurements and related tests were performed. After ultrasonic cleaning, the SEYs of laser treated aluminum alloy increased from 0.99, 1.05, and 1.16 to 1.43, 1.74, and 1.38, respectively. Compared to the surface roughness of uncleaned laser treated aluminum samples, the cleaned laser treated ones decreased from 10.7, 7.5, and 14.5 to 9.4, 6.9, and 12.9, respectively. The results indicate that ultrasonic cleaning can induce the SEY increase of laser processed aluminum alloy. The correlative mechanism between the surface morphology, the surface chemistry, and SEY increase were analyzed for the first time.

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Monte Carlo Modelling of Secondary Electron Yield from Rough Surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100180860 ◽

1990 ◽

Vol 48 (1) ◽

pp. 422-423

Author(s):

John C. Russ

Keyword(s):

Monte Carlo ◽

Energy Loss ◽

Secondary Electron ◽

Secondary Electron Emission ◽

Analytical Calculation ◽

Mean Free Path ◽

Single Scattering ◽

High Energy ◽

Secondary Electron Yield ◽

Electron Yield

Monte-Carlo programs are well recognized for their ability to model electron beam interactions with samples, and to incorporate boundary conditions such as compositional or surface variations which are difficult to handle analytically. This success has been especially powerful for modelling X-ray emission and the backscattering of high energy electrons. Secondary electron emission has proven to be somewhat more difficult, since the diffusion of the generated secondaries to the surface is strongly geometry dependent, and requires analytical calculations as well as material parameters. Modelling of secondary electron yield within a Monte-Carlo framework has been done using multiple scattering programs, but is not readily adapted to the moderately complex geometries associated with samples such as microelectronic devices, etc.This paper reports results using a different approach in which simplifying assumptions are made to permit direct and easy estimation of the secondary electron signal from samples of arbitrary complexity. The single-scattering program which performs the basic Monte-Carlo simulation (and is also used for backscattered electron and EBIC simulation) allows multiple regions to be defined within the sample, each with boundaries formed by a polygon of any number of sides. Each region may be given any elemental composition in atomic percent. In addition to the regions comprising the primary structure of the sample, a series of thin regions are defined along the surface(s) in which the total energy loss of the primary electrons is summed. This energy loss is assumed to be proportional to the generated secondary electron signal which would be emitted from the sample. The only adjustable variable is the thickness of the region, which plays the same role as the mean free path of the secondary electrons in an analytical calculation. This is treated as an empirical factor, similar in many respects to the λ and ε parameters in the Joy model.

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Quantitative Microprobe Analysis by Means of Target Current Measurements*

Advances in X-ray Analysis ◽

10.1154/s0376030800004602 ◽

1966 ◽

Vol 10 ◽

pp. 447-461 ◽

Cited By ~ 3

Author(s):

J. W. Colby ◽

W. N. Wise ◽

D. K. Conley

Keyword(s):

Binary Systems ◽

Secondary Electron ◽

Surface Condition ◽

Energy Levels ◽

Target Material ◽

High Energy ◽

Secondary Electrons ◽

Secondary Electron Yield ◽

Electron Yield ◽

Electron Backscatter

AbstractIn the microprobe analyzer, a portion of the high energy electrons impinging on the surface are backscattered from the sample and re-emitted at high energy levels. Low energy (less than 50 eV) or secondary electrons also ate emitted. Both the electron backscatter yield and the secondary electron yield are related to the mean atomic number of the target material and, hence, may be used to provide information about the target composition. Unfortunately, however, the secondary electron yield is very sensitive to the surface condition of the specimen and various instrument parameters. This complicates the otherwise simple linear relationship between sample composition and electron backscatter yield.It is shown that the effects due to secondary electrons can be minimized by biasing the sample, and that good results can be obtained in the analysis of binary systems. The limitations and utility of the method are discussed, and backscatter yields are determined.

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Comparison of Carbon Thin Films with Low Secondary Electron Yield Deposited in Neon and Argon

Coatings ◽

10.3390/coatings10090884 ◽

2020 ◽

Vol 10 (9) ◽

pp. 884

Author(s):

Yuxin Zhang ◽

Yigang Wang ◽

Sihui Wang ◽

Wei Wei ◽

Xiaoqin Ge ◽

...

Keyword(s):

Thin Films ◽

Raman Spectroscopy ◽

Amorphous Carbon ◽

Secondary Electron ◽

High Energy ◽

Carbon Coatings ◽

Secondary Electron Yield ◽

Electron Yield ◽

Carbon Thin Films ◽

Amorphous Carbon Coatings

Modification of vacuum chamber surface properties by introducing a layer of material with low secondary electron yield (SEY) is one of the most useful solutions to suppress the electron-cloud in high-energy particle accelerators. In the present work, amorphous carbon thin films have been produced by DC magnetron sputtering with Neon and Argon sputtering gases. Microstructures of the thin films have been characterized by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The sp2 and sp3 hybridized carbon atoms are evaluated using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The amorphous carbon coatings comprise tiny granularities of tens of nanometers. The amorphous carbon films show more graphite-like properties as revealed by XPS and Raman spectroscopy. The secondary electron emission measurement results indicate that amorphous carbon coatings present SEY of <1.2. The thin film deposited by Ne exhibits a higher sp2 hybridization content, leading to a slightly lower SEY compared with the film produced with Ar.

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Secondary Electron Yield from Al by High-Energy Primary Electrons

Physical Review ◽

10.1103/physrev.96.35 ◽

1954 ◽

Vol 96 (1) ◽

pp. 35-35 ◽

Cited By ~ 10

Author(s):

G. W. Tautfest ◽

H. R. Fechter

Keyword(s):

Secondary Electron ◽

High Energy ◽

Secondary Electron Yield ◽

Electron Yield ◽

Primary Electrons

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Die Sekundärelektronen-Ausbeute verschiedener Materialien bei Beschuß mit leichten Ionen hoher Energie / Secondary Electron Yield from Various Materials under the Impact of Light Ions at High Energies

Zeitschrift für Naturforschung A ◽

10.1515/zna-1975-0810 ◽

1975 ◽

Vol 30 (8) ◽

pp. 981-985

Author(s):

H. P. Beck ◽

R. Langkau

Keyword(s):

Secondary Electron ◽

Low Energy ◽

Secondary Electrons ◽

Secondary Electron Yield ◽

High Energies ◽

Electron Yield ◽

Light Ions ◽

The Impact ◽

Theoretical Considerations

Abstract The backward emission of secondary electrons from thick targets of graphite, aluminum, copper, molybdenum and tantalum under the impact of protons, deuterons, 3 He-ions and a-particles has been measured for incident energies in the MeV-range. The data are discussed within the scope of theoretical considerations based on low-energy studies taking into account the contribution due to ;< 5-rays.

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