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Explanation of Sextupole Instability in CERN PS Booster

Dual harmonic RF systems have been discussed for many years: to promote Landau damping, to reduce transverse space-charge, and to improve Touschek lifetime. Since its introduction into the CPS booster in 1982, the dual harmonic acceleration process suffered from an unexplained longitudinal instabili...

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Detalles Bibliográficos
Autores principales: Blas, A, Koscielniak, Shane Rupert, Pedersen, F
Lenguaje:eng
Publicado: 1998
Materias:
Acceso en línea:http://cds.cern.ch/record/363823
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author Blas, A
Koscielniak, Shane Rupert
Pedersen, F
author_facet Blas, A
Koscielniak, Shane Rupert
Pedersen, F
author_sort Blas, A
collection CERN
description Dual harmonic RF systems have been discussed for many years: to promote Landau damping, to reduce transverse space-charge, and to improve Touschek lifetime. Since its introduction into the CPS booster in 1982, the dual harmonic acceleration process suffered from an unexplained longitudinal instability occurring when the 2nd harmonic cavity is anti-phased and controlled by the 1st harmonic gap signa l. The instability does not occur when the beam fundamental is used as reference, nor when the RF harmonics are in-phase. The impetus for the present study arises from the conversion from harmonic num bers h=5 and 10 to h=1 and 2 for LHC operation. The instability has recently been diagnosed as a sextupole mode. In this paper, which is a synopsis of two laboratory notes [3,4], are presented experim ental results from machine development (MD) periods, and a detailed theoretical explanation for the instability (and its correction) that considers feedback from the beam versus the cavity fundamental .
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institution Organización Europea para la Investigación Nuclear
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publishDate 1998
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spelling cern-3638232021-11-11T09:54:36Zhttp://cds.cern.ch/record/363823engBlas, AKoscielniak, Shane RupertPedersen, FExplanation of Sextupole Instability in CERN PS BoosterAccelerators and Storage RingsDual harmonic RF systems have been discussed for many years: to promote Landau damping, to reduce transverse space-charge, and to improve Touschek lifetime. Since its introduction into the CPS booster in 1982, the dual harmonic acceleration process suffered from an unexplained longitudinal instability occurring when the 2nd harmonic cavity is anti-phased and controlled by the 1st harmonic gap signa l. The instability does not occur when the beam fundamental is used as reference, nor when the RF harmonics are in-phase. The impetus for the present study arises from the conversion from harmonic num bers h=5 and 10 to h=1 and 2 for LHC operation. The instability has recently been diagnosed as a sextupole mode. In this paper, which is a synopsis of two laboratory notes [3,4], are presented experim ental results from machine development (MD) periods, and a detailed theoretical explanation for the instability (and its correction) that considers feedback from the beam versus the cavity fundamental .CERN-PS-98-028-RFoai:cds.cern.ch:3638231998-07-20
spellingShingle Accelerators and Storage Rings
Blas, A
Koscielniak, Shane Rupert
Pedersen, F
Explanation of Sextupole Instability in CERN PS Booster
title Explanation of Sextupole Instability in CERN PS Booster
title_full Explanation of Sextupole Instability in CERN PS Booster
title_fullStr Explanation of Sextupole Instability in CERN PS Booster
title_full_unstemmed Explanation of Sextupole Instability in CERN PS Booster
title_short Explanation of Sextupole Instability in CERN PS Booster
title_sort explanation of sextupole instability in cern ps booster
topic Accelerators and Storage Rings
url http://cds.cern.ch/record/363823
work_keys_str_mv AT blasa explanationofsextupoleinstabilityincernpsbooster
AT koscielniakshanerupert explanationofsextupoleinstabilityincernpsbooster
AT pedersenf explanationofsextupoleinstabilityincernpsbooster