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Geometric beam coupling impedance of LHC secondary collimators

The High Luminosity LHC project is aimed at increasing the LHC luminosity by an order of magnitude. One of the key ingredients to achieve the luminosity goal is the beam intensity increase. In order to keep under control beam instabilities and to avoid excessive power losses a careful design of new...

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Autores principales: Frasciello, Oscar, Tomassini, Sandro, Zobov, Mikhail, Grudiev, A, Mounet, N, Salvant, B
Lenguaje:eng
Publicado: 2014
Materias:
Acceso en línea:http://cds.cern.ch/record/2262869
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author Frasciello, Oscar
Tomassini, Sandro
Zobov, Mikhail
Grudiev, A
Mounet, N
Salvant, B
author_facet Frasciello, Oscar
Tomassini, Sandro
Zobov, Mikhail
Grudiev, A
Mounet, N
Salvant, B
author_sort Frasciello, Oscar
collection CERN
description The High Luminosity LHC project is aimed at increasing the LHC luminosity by an order of magnitude. One of the key ingredients to achieve the luminosity goal is the beam intensity increase. In order to keep under control beam instabilities and to avoid excessive power losses a careful design of new vacuum chamber components and an improvement of the present LHC impedance model are required. Collimators are the main impedance contributors. Measurements with beam have revealed that the betatron coherent tune shifts were by about a factor of 2 higher with respect to the theoretical predictions based on the current model. Up to now the resistive wall impedance has been considered as the major impedance contribution for collimators. By carefully simulating their geometric impedance we show that for the graphite collimators with half-gaps higher than 10 mm the geometric impedance exceeds the resistive wall one. In turn, for the tungsten collimators the geometric impedance dominates for all used gap values. Hence, including the geometric collimator impedance into the LHC impedance model enabled us to reach a better agreement between the measured and simulated collimator tune shifts.
id oai-inspirehep.net-1428600
institution Organización Europea para la Investigación Nuclear
language eng
publishDate 2014
record_format invenio
spelling oai-inspirehep.net-14286002019-09-30T06:29:59Zhttp://cds.cern.ch/record/2262869engFrasciello, OscarTomassini, SandroZobov, MikhailGrudiev, AMounet, NSalvant, BGeometric beam coupling impedance of LHC secondary collimatorsAccelerators and Storage RingsThe High Luminosity LHC project is aimed at increasing the LHC luminosity by an order of magnitude. One of the key ingredients to achieve the luminosity goal is the beam intensity increase. In order to keep under control beam instabilities and to avoid excessive power losses a careful design of new vacuum chamber components and an improvement of the present LHC impedance model are required. Collimators are the main impedance contributors. Measurements with beam have revealed that the betatron coherent tune shifts were by about a factor of 2 higher with respect to the theoretical predictions based on the current model. Up to now the resistive wall impedance has been considered as the major impedance contribution for collimators. By carefully simulating their geometric impedance we show that for the graphite collimators with half-gaps higher than 10 mm the geometric impedance exceeds the resistive wall one. In turn, for the tungsten collimators the geometric impedance dominates for all used gap values. Hence, including the geometric collimator impedance into the LHC impedance model enabled us to reach a better agreement between the measured and simulated collimator tune shifts.IPAC-2014-TUPRI049oai:inspirehep.net:14286002014
spellingShingle Accelerators and Storage Rings
Frasciello, Oscar
Tomassini, Sandro
Zobov, Mikhail
Grudiev, A
Mounet, N
Salvant, B
Geometric beam coupling impedance of LHC secondary collimators
title Geometric beam coupling impedance of LHC secondary collimators
title_full Geometric beam coupling impedance of LHC secondary collimators
title_fullStr Geometric beam coupling impedance of LHC secondary collimators
title_full_unstemmed Geometric beam coupling impedance of LHC secondary collimators
title_short Geometric beam coupling impedance of LHC secondary collimators
title_sort geometric beam coupling impedance of lhc secondary collimators
topic Accelerators and Storage Rings
url http://cds.cern.ch/record/2262869
work_keys_str_mv AT frasciellooscar geometricbeamcouplingimpedanceoflhcsecondarycollimators
AT tomassinisandro geometricbeamcouplingimpedanceoflhcsecondarycollimators
AT zobovmikhail geometricbeamcouplingimpedanceoflhcsecondarycollimators
AT grudieva geometricbeamcouplingimpedanceoflhcsecondarycollimators
AT mounetn geometricbeamcouplingimpedanceoflhcsecondarycollimators
AT salvantb geometricbeamcouplingimpedanceoflhcsecondarycollimators