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Experimental Evidence of Boundary Induced Coupling Currents in LHC Prototypes
The field quality of 10 m long LHC dipole models has been measured with short rotating coils to explore its dependence on time and position. Multipoles exhibit a longitudinal periodic variation, with period equal to the twist pitch length. This periodicity is shown here to have at least two componen...
Autores principales: | , , |
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Lenguaje: | eng |
Publicado: |
1996
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Acceso en línea: | https://dx.doi.org/10.1109/77.614624 http://cds.cern.ch/record/311043 |
_version_ | 1780890089097789440 |
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author | Bottura, L Walckiers, L Ang, Z |
author_facet | Bottura, L Walckiers, L Ang, Z |
author_sort | Bottura, L |
collection | CERN |
description | The field quality of 10 m long LHC dipole models has been measured with short rotating coils to explore its dependence on time and position. Multipoles exhibit a longitudinal periodic variation, with period equal to the twist pitch length. This periodicity is shown here to have at least two components with very different time constants. The amplitude of the component with the shorter time constant, in the range of 100 to 300 s, depends on position and time. Larger amplitudes are measured at early times after a ramp and close to regions with incomplete cable transposition with respect to the non-uniform external field change. As the multipoles periodicity is due to current imbalance in the cables, we attribute the short time scale variations to the presence of space and time decaying boundary induced coupling currents (BICC's) in the cable. An estimate of their value is given |
id | cern-311043 |
institution | Organización Europea para la Investigación Nuclear |
language | eng |
publishDate | 1996 |
record_format | invenio |
spelling | cern-3110432023-05-31T13:22:03Zdoi:10.1109/77.614624http://cds.cern.ch/record/311043engBottura, LWalckiers, LAng, ZExperimental Evidence of Boundary Induced Coupling Currents in LHC PrototypesAccelerators and Storage RingsThe field quality of 10 m long LHC dipole models has been measured with short rotating coils to explore its dependence on time and position. Multipoles exhibit a longitudinal periodic variation, with period equal to the twist pitch length. This periodicity is shown here to have at least two components with very different time constants. The amplitude of the component with the shorter time constant, in the range of 100 to 300 s, depends on position and time. Larger amplitudes are measured at early times after a ramp and close to regions with incomplete cable transposition with respect to the non-uniform external field change. As the multipoles periodicity is due to current imbalance in the cables, we attribute the short time scale variations to the presence of space and time decaying boundary induced coupling currents (BICC's) in the cable. An estimate of their value is givenLHC-Project-Report-54CERN-LHC-Project-Report-54oai:cds.cern.ch:3110431996-09-18 |
spellingShingle | Accelerators and Storage Rings Bottura, L Walckiers, L Ang, Z Experimental Evidence of Boundary Induced Coupling Currents in LHC Prototypes |
title | Experimental Evidence of Boundary Induced Coupling Currents in LHC Prototypes |
title_full | Experimental Evidence of Boundary Induced Coupling Currents in LHC Prototypes |
title_fullStr | Experimental Evidence of Boundary Induced Coupling Currents in LHC Prototypes |
title_full_unstemmed | Experimental Evidence of Boundary Induced Coupling Currents in LHC Prototypes |
title_short | Experimental Evidence of Boundary Induced Coupling Currents in LHC Prototypes |
title_sort | experimental evidence of boundary induced coupling currents in lhc prototypes |
topic | Accelerators and Storage Rings |
url | https://dx.doi.org/10.1109/77.614624 http://cds.cern.ch/record/311043 |
work_keys_str_mv | AT bottural experimentalevidenceofboundaryinducedcouplingcurrentsinlhcprototypes AT walckiersl experimentalevidenceofboundaryinducedcouplingcurrentsinlhcprototypes AT angz experimentalevidenceofboundaryinducedcouplingcurrentsinlhcprototypes |