CERN Accelerating science

Published Articles
Title	Single Bunch Instabilities and NEG Coating for FCC-ee
Author(s)	Belli, Eleonora (Rome U.) ; Costa Pinto, Pedro (CERN) ; Migliorati, Mauro (INFN, Rome) ; Rumolo, Giovanni (CERN) ; Sapountzis, Antonios (CERN) ; Sinkovits, Theo (CERN) ; Taborelli, Mauro (CERN) ; Zobov, Mikhail (Frascati)
Publication	JACOW, 2019
Number of pages	7
In:	62nd ICFA Advanced Beam Dynamics Workshop on High Luminosity Circular e+e− Colliders, Hong Kong, China, 24 - 27 Sep 2018, pp.WEOAB04
DOI	10.18429/JACoW-eeFACT2018-WEOAB04
Subject category	Accelerators and Storage Rings
Abstract	The high luminosity electron-positron collider FCC-ee is part of the Future Circular Collider (FCC) study at CERN and it has been designed to cover the beam energy range from 45.6 GeV to 182.5 GeV to study the properties of the Higgs boson and other particles. Electron cloud build up simulations on the Z resonance revealed the necessity of minimising the Secondary Electron Yield (SEY) of the pipe walls by applying a Ti-Zr-V Non-Evaporable Getter (NEG) coating in the entire ring. Beam dynamics simulations at 45.6 GeV pointed out that minimising the thickness of this layer is mandatory to reduce the resistive wall (RW) impedance, thus increasing the single bunch instability thresholds and ensuring beam stability during operation. However, reducing the coating thickness can affect the performance of the material and therefore the SEY. For this reason, an extensive measurement campaign was performed at CERN to characterise NEG thin films with thicknesses below 250 nm in terms of activation performance and SEY measurements. This paper also presents the FCC-ee longitudinal impedance model which includes all the current machine components.
Copyright/License	publication: © 2018-2024 Authors (License: CC-BY-3.0)

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