| Paper | Title | Page |
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TUT3AH0 |
Low SEY Engineered Surface for Electron Cloud Eradication | |
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| Developing a surface with low Secondary Electron Yield (SEY) is one of the principal methods of mitigating the beam-induced electron multipacting and electron cloud in high-energy charged particle accelerators. Since the wall material, surface chemistry, topography and electron energy are the parameters that influence the SEY, common mitigation mechanisms are based on engineering the above parameters. Recently ASTeC has demonstrated that nano- and microstructures engineered on Cu, Al and Stainless steel surface reduces SEY to less than 1. Such structures can be readily produced by nano- and sub-nanosecond pulsed laser. SEY can be further reduced to an even lower value by bake-out and/or photon and/or electron bombardment. A systematic analysis of surface composition and chemistry (using XPS), the surface topography (using SEM), and SEY measurements with primary electron energies ranging from 50 to 1000 eV is reported and correlated to the laser treatment conditions. A test liner was prepared by ASTeC for a first machine test of such new anti-e-cloud technique. The liner has been installed at SPS for testing in the LHC-like beam conditions. | ||
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WET3AH1 |
Progress in NEG Coatings for Particle Accelerators | |
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| This talk will overview recent progress in developing of non-evaporable getter (NEG) coatings. NEG coatings are widely used in particle accelerator as a complex solution which addresses a few problems. It is a barrier for gas diffusion from the vacuum chamber material, it reduces photon and electron stimulated desorption by an order of magnitude. It provides a distributed pumping speed, making NEG is the most economical and, in many cases, the only vacuum solution for long and narrow vacuum chambers. Another important property of NEG coating is its low SEY (after NEG activation), so it reduces a risk of e-cloud and beam induced electron mitipacting. The NEG coating surface resistance was recently studied in ASTeC. New experimental data and a model allow calculating NEG coating impedance in wide range of RF frequencies. | ||
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