CERN Accelerating science

Published Articles
Report number	CERN-ACC-2018-147
Title	Low-Impedance Collimators for HL-LHC
Author(s)	Antipov, Sergey (CERN) ; Amorim, David (U. Grenoble Alpes) ; Bertarelli, A (CERN) ; Biancacci, Nicolo (CERN) ; Bruce, Roderik (CERN) ; Mereghetti, Alessio (CERN) ; Mirarchi, Daniele (CERN) ; Métral, Elias (CERN) ; Redaelli, Stefano (CERN) ; Salvant, Benoit (CERN)
Publication	2018
Number of pages	4
In:	9th International Particle Accelerator Conference, Vancouver, Canada, 29 Apr - 4 May 2018, pp.WEYGBE4
DOI	10.18429/JACoW-IPAC2018-WEYGBE4
Subject category	Accelerators and Storage Rings
Project	CERN HL-LHC
Abstract	The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) will double its beam intensity for the needs of High Energy Physics frontier. This increase requires a reduction of the machine's impedance to ensure the coherent stability of the beams until they are put in collision. A major part of the impedance is the resistive wall contribution of the collimators. To reduce this contribution several coating options have been proposed. We have studied numerically the effect of the novel coatings on the beam stability. The results show that a decrease of up to 30% of the machine impedance and a reduction of up to 120 A in the stabilizing octupole current threshold can be achieved by coating the secondary collimators with Molybdenum. Half of that improvement can be obtained by coating the jaws of a subset of four collimators identified as the highest contributors to machine impedance. The installation of this subset of low-impedance collimators is planned for the Long Shutdown 2 in 2019-2020.
Copyright/License	CC-BY-3.0

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