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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...
Autores principales: | , , , , , |
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Lenguaje: | eng |
Publicado: |
2014
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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 |