Space charge effects in bunches for different rf wave forms

Shukla, Tripti

doi:10.1103/physrevstab.8.034201

Cited by 25 publications

(33 citation statements)

References 15 publications

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“…In a realistic bunch in experiment, the bunch profile is normally different from an analytic model, thus we consider here another bunch form for comparison. For a parabolic longitudinal distribution (or elliptic bunch) with the total half-length p ¼ ffiffiffi 5 p z one obtains the analytic expression [6], …”

Section: A Longitudinal Dipole Frequencymentioning

confidence: 99%

“…It should be however mentioned that other choices for the characteristic synchrotron frequency in long bunches are possible and can be useful depending on the consideration contents. The frequency of smallamplitude dipole oscillations can be calculated as [4,6] …”

Section: A Longitudinal Dipole Frequencymentioning

confidence: 99%

“…An important parameter for head-tail bunch oscillations in long bunches [4][5][6] is the effective synchrotron frequency which will be different from the small-amplitude synchrotron frequency in short bunches. We will show that in long bunches the longitudinal dipole frequency Q dip f 0 can be chosen as a substitute for the small-amplitude incoherent synchrotron frequency Q s0 f 0 .…”

Section: A Longitudinal Dipole Frequencymentioning

confidence: 99%

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Transverse decoherence and coherent spectra in long bunches with space charge

Kornilov

2012

Phys. Rev. ST Accel. Beams

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The transverse bunch spectrum and the transverse decoherence/recoherence following an initial bunch offset are important phenomena in synchrotrons and storage rings, and are widely used for beam and lattice measurements. Incoherent shifts of the particles betatron frequency and of the synchrotron frequency modify the transverse spectrum and the bunch decoherence. In this study we analyze the effects of transverse space charge and of the rf nonlinearity on the decoherence signals. The transverse bunch decoherence and the resulting coherent spectra are measured in the SIS18 synchrotron at GSI Darmstadt for different bunch parameters. The frequencies of the bunch head-tail modes provide a direct measure for the self-field space charge tune shift. Particle tracking simulations together with an analytical model are used to describe the modifications in the decoherence signals and in the coherent spectra due to space charge and the rf bucket nonlinearity.

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Section: A Longitudinal Dipole Frequencymentioning

confidence: 99%

Section: A Longitudinal Dipole Frequencymentioning

confidence: 99%

Section: A Longitudinal Dipole Frequencymentioning

confidence: 99%

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Transverse decoherence and coherent spectra in long bunches with space charge

Kornilov

2012

Phys. Rev. ST Accel. Beams

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“…6. A similar effect was observed in numerical simulations for a double RF system with space-charge effects included [11].…”

Section: Beam Transfer Functionssupporting

confidence: 62%

Beam Transfer Functions and Beam Stabilisation in a Double RF System

Shaposhnikova

Bohl²,

Linnecar³

Proceedings of the 2005 Particle Accelerator Conference

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The high intensity proton beam for LHC accelerated in the CERN SPS is stabilised against coupled-bunch instabilities by a 4th harmonic RF system in bunch-shortening mode. Bunch-lengthening mode, which could also be useful to reduce peak line density and alleviate problems from e-cloud and kicker heating, does not give desirable results for beam stability. In this paper an analysis of the limitations of these two different modes of operation is presented together with measurements of the Beam Transfer Function for the double RF system. As predicted by theory, for sufficiently long bunches with the same noise excitation, the measured amplitude of the beam response in bunchlengthening mode is an order of magnitude higher than that for bunch-shortening mode or for a single RF system. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH CERN -AB Department BEAM TRANSFER FUNCTIONS AND BEAM STABILISATION IN A DOUBLE RF SYSTEME. Shaposhnikova, T. Bohl and T. Linnecar, CERN, Geneva, Switzerland AbstractThe high intensity proton beam for LHC accelerated in the CERN SPS is stabilised against coupled-bunch instabilities by a 4th harmonic RF system in bunch-shortening mode. Bunch-lengthening mode, which could also be useful to reduce peak line density and alleviate problems from e-cloud and kicker heating, does not give desirable results for beam stability. In this paper an analysis of the limitations of these two different modes of operation is presented together with measurements of the Beam Transfer Function for the double RF system. As predicted by theory, for sufficiently long bunches with the same noise excitation, the measured amplitude of the beam response in bunchlengthening mode is an order of magnitude higher than that for bunch-shortening mode or for a single RF system.

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“…For an elliptic bunch distribution (parabolic bunch profile) with the bunch halflength m ¼ ffiffiffi 5 p l (rms bunch length l ), one obtains the approximate analytic expression for the longitudinal dipole tune [15],…”

Section: Tune Spectrum For High Intensitymentioning

confidence: 99%

Interpretation of transverse tune spectra in a heavy-ion synchrotron at high intensities

Singh

Chorniy

Forck

et al. 2013

Phys. Rev. ST Accel. Beams

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Two different tune measurement systems have been installed in the GSI Helmholtzzentrum für Schwerionenforschung heavy-ion synchrotron SIS-18. Tune spectra are obtained with high accuracy using these fast and sensitive systems. Besides the machine tune, the spectra contain information about the intensity dependent coherent tune shift and the incoherent space charge tune shift. The space charge tune shift is derived from a fit of the observed shifted positions of the synchrotron satellites to an analytic expression for the head-tail eigenmodes with space charge. Furthermore, the chromaticity is extracted from the measured head-tail mode structure. The results of the measurements provide experimental evidence of the importance of space charge effects and head-tail modes for the interpretation of transverse beam signals at high intensity.

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Space charge effects in bunches for different rf wave forms

Cited by 25 publications

References 15 publications

Transverse decoherence and coherent spectra in long bunches with space charge

Transverse decoherence and coherent spectra in long bunches with space charge

Beam Transfer Functions and Beam Stabilisation in a Double RF System

Interpretation of transverse tune spectra in a heavy-ion synchrotron at high intensities

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