Effect of the surface processing on the secondary electron yield of Al alloy samples

Grosso, D.R.; Commisso, M.; Cimino, R.; Larciprete, R.; Flammini, R.; Wanzenberg, Rainer

doi:10.1103/physrevstab.16.051003

Cited by 13 publications

(9 citation statements)

References 25 publications

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“…In the design of the setups used to perform such experiments and presently in operation at the Material Science INFN-LNF laboratory of Frascati (Roma), great care has been taken to eliminate spurious effects affecting the determination of LE-SEY. The experimental setup, described in details elsewhere [5,7,8,[14][15][16][17]29], can operate in UHV (background pressure below 10 −10 mbar). The use of a μ-metal chamber reduces to less than 5 mG the residual magnetic field at the sample position.…”

Section: Methodsmentioning

confidence: 99%

“…is an accurate measure of the surface work function W s (for metals) and χ s þ E GAP (for semiconductors and insulators) of the new sample under analysis with respect to W Cu . For completeness, we mention here that in [5,7,8,[14][15][16][17]29], as well as in most literature on SEY, as reported in [7], the energy scale of the landing electrons was referenced to be zero at E p ¼ W s or χ s þ E GAP without considering their variation for all samples and sample preparations. This would not significantly alter the conclusions of those papers, since it introduced only a small energy offset between different experiments.…”

Section: A Energy Referencementioning

confidence: 99%

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Detailed investigation of the low energy secondary electron yield of technical Cu and its relevance for the LHC

Cimino

Gonzalez

Iadarola

et al. 2015

Phys. Rev. ST Accel. Beams

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The detailed study of the low energy secondary electron yield (LE-SEY) of technical Cu for low electron energies (from 0 to 20 eV) is very important for electron cloud build up in high intensity accelerators and in many other fields of research. Different devices base their functionalities on the number of electrons produced by a surface when hit by other electrons, namely its SEY, and, in most cases, on its very low energy behavior. However, LE-SEY has been rarely addressed due to the intrinsic experimental complexity to control very low energy electrons. Furthermore, several results published in the past have been recently questioned, allegedly suffering from experimental systematics. Here, we critically review the experimental method used to study LE-SEY and precisely define the energy region in which the experimental data can be considered valid. By analyzing the significantly different behavior of LE-SEY in clean polycrystalline Cu (going toward zero at zero impinging energies) and in its as received technical counterpart (maintaining a significant value in the entire region), we solve most, if not all, of the apparent controversy present in the literature, producing important inputs for better understanding the device performances related to their LE-SEY. Simulations are then performed to address the impact of such results on electron cloud predictions in the LH

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Section: Methodsmentioning

confidence: 99%

Section: A Energy Referencementioning

confidence: 99%

Detailed investigation of the low energy secondary electron yield of technical Cu and its relevance for the LHC

Cimino

Gonzalez

Iadarola

et al. 2015

Phys. Rev. ST Accel. Beams

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“…By comparing with the blue curve of uncoated and untreated aluminum alloy sample in Figure 7f, it can be seen that the maximum SEY of the blue curve in Figure 7a of uncoated laser-treated sample #1 with a pitch spacing of 15 µm and that of the blue curve in Figure 7b of uncoated laser-treated sample #2 with a pitch spacing of 20 µm decreased from 2.30 to 1.04 and 1.13, respectively. The δ max of as-received bare aluminum alloy reported by several other researchers from Science and Technology Facilities Council (STFC) Daresbury Laboratory, National Institute for Nuclear Physics (INFN), German Electron Synchrotron (DESY) and European Organization for Nuclear Research (CERN) varied between 2.55 and 3.50 [10,[28][29][30]. The δ max difference of the untreated aluminum alloy might be related to the surface morphology and the oxide thickness of the surface.…”

Section: Secondary Electron Yield (Sey) Resultsmentioning

confidence: 99%

Non-Evaporable Getter Ti-V-Hf-Zr Film Coating on Laser-Treated Aluminum Alloy Substrate for Electron Cloud Mitigation

Wang¹,

Gao²,

You³

et al. 2019

Coatings

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For improving the vacuum and mitigating the electron clouds in ultra-high vacuum chamber systems of high-energy accelerators, the deposition of Ti-V-Hf-Zr getter film on a laser-treated aluminum alloy substrate was proposed and exploited for the first time in this study. The laser-treated aluminum surface exhibits a low secondary electron yield (SEY), which is even lower than 1 for some selected laser parameters. Non-evaporable getter (NEG) Ti-V-Hf-Zr film coatings were prepared using the direct current (DC) sputtering method. The surface morphology, surface roughness and composition of Ti-V-Hf-Zr getter films were characterized and analyzed. The maximum SEY of unactivated Ti-V-Hf-Zr getter film on laser-treated aluminum alloy substrates ranged from 1.10 to 1.48. The X-ray photoelectron spectroscopy (XPS) spectra demonstrate that the Ti-V-Hf-Zr coated laser-treated aluminum alloy could be partially activated after being heated at 100 and 150 °C, respectively, for 1 h in a vacuum and also used as a pump. The results were demonstrated initially and the potential application should be considered in future particle accelerators.

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“…If the number of free electrons becomes significant, it can degrade the particle beam, or cause an increase in pressure inside the beam tube. In order to mitigate the creation of an electron cloud, studies [34,42] have measured the effect of the prolonged exposure of the surface to the electron beam. For example, the copper samples were exposed to an electron beam of 500 eV of primary energy while the beam current was in the order of 1 to 5 μA [34].…”

Section: Influence Of Electron Beam Irradiation On Seymentioning

confidence: 99%

“…A similar study was performed on the aluminum sample, where a single spot of 1 mm 2 was irradiated [42]. Energy of the primary electrons in the beam during irradiation was kept constant at 500 eV while the beam current was in the order of 1 to 5 μA.…”

Section: Influence Of Electron Beam Irradiation On Seymentioning

confidence: 99%

Secondary Electron Emission from Plasma Processed Accelerating Cavity Grade Niobium

Basovic

2016

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Advances in the particle accelerator technology have enabled numerous fundamental discoveries in 20th century physics. Extensive interdisciplinary research has always supported further development of accelerator technology in efforts of reaching each new energy frontier. Accelerating cavities, which are used to transfer energy to accelerated charged particles, have been one of the main focuses of research and development in the particle accelerator field. Over the last fifty years, in the race to break energy barriers, there has been constant improvement of the maximum stable accelerating field achieved in accelerating cavities. Every increase in the maximum attainable accelerating fields allowed for higher energy upgrades of existing accelerators and more compact designs of new accelerators. Each new and improved technology was faced with ever emerging limiting factors. With the standard high accelerating gradients of more than 25 MV/m, free electrons inside the cavities get accelerated by the field, gaining enough energy to produce more electrons in their interactions with the walls of the cavity. The electron production is exponential and the electron energy transfer to the walls of a cavity can trigger detrimental processes, limiting the performance of the cavity. The root cause of the free electron number gain is a phenomenon called Secondary Electron Emission (SEE). Even though the phenomenon has been known and studied over a century, there are still no effective means of controlling it. The ratio between the 1 Jefferson Laboratory is operated by Jefferson Science Associates under DOE Contract No. DE-AC05-06OR23177. viii NOMENCLATURE SEE Secondary electron emission SEY Secondary electron yield SRF Superconducting radio frequency Tc Critical temperature for superconductivity RRR Residual resistivity ratio Eacc Accelerating gradient Vacc Accelerating voltage d Length of the cavity Q0 Intrinsic quality factor ω Angular resonant frequency U Energy stored by electromagnetic field Pc Dissipated power rf radiofrequency BCP Buffered chemical polishing ECP Electro-chemical polishing HPR High pressure rinsing SEM Scanning electron microscope δ SEY δmax Maximum SEY E0 Primary electron energy E0I Primary electron energy of the first crossover point E0II Primary electron energy of the second crossover point ix E0max Primary electron energy at maximum SEY EDC Energy distribution curve θ Incident angle of the primary electrons WZ Weld zone HAZ Heat affected zone BASE Base metal surface, sample set R-HAZ Heat treated base metal surface WELD Sample set OFFSET Sample set ip Primary electron beam current is Sample current ic Collector current XPS X-ray photoelectron spectroscopy RGA Residual gas analyzer SIMS Secondary ion mass spectroscopy (x), (y), (z) Translational axes of motion R(y) Rotational motion around (y) axis GUI Graphical user interface Uc Collector bias voltage Us Sample bias voltage PBC Primary beam collector iBP Current of the back plate iFP Current of the front plate x A Ratio of the iBP, and sum of the iBP a...

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Effect of the surface processing on the secondary electron yield of Al alloy samples

Cited by 13 publications

References 25 publications

Detailed investigation of the low energy secondary electron yield of technical Cu and its relevance for the LHC

Detailed investigation of the low energy secondary electron yield of technical Cu and its relevance for the LHC

Non-Evaporable Getter Ti-V-Hf-Zr Film Coating on Laser-Treated Aluminum Alloy Substrate for Electron Cloud Mitigation

Secondary Electron Emission from Plasma Processed Accelerating Cavity Grade Niobium

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