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The damping of transverse coherent instabilities by harmonic cavities

Cullinan, F. J.; Nagaoka, Ryutaro; Skripka, G. LU and Fernandes Tavares, Pedro LU (2015) 6th International Particle Accelerator Conference, IPAC 2015 In 6th International Particle Accelerator Conference, IPAC 2015 p.102-105
Abstract

At nonzero chromaticity, the threshold current due to transverse coupled bunch instabilities in an electron storage ring is defined by intrabunch head-tail motion of higher than zeroth order. Multibunch tracking simulations predict that this threshold can be increased to several times its original value through the introduction of bunch lengthening harmonic cavities. One previously suggested explanation is the narrower spectra of the elongated bunches but reliable estimates for the threshold currents are not obtainable for anything other than rigid beam motion since the usual Sacherer formalism is not directly applicable to beams in a non-harmonic potential. A new scheme has been developed in which the decay time of a higher than zeroth... (More)

At nonzero chromaticity, the threshold current due to transverse coupled bunch instabilities in an electron storage ring is defined by intrabunch head-tail motion of higher than zeroth order. Multibunch tracking simulations predict that this threshold can be increased to several times its original value through the introduction of bunch lengthening harmonic cavities. One previously suggested explanation is the narrower spectra of the elongated bunches but reliable estimates for the threshold currents are not obtainable for anything other than rigid beam motion since the usual Sacherer formalism is not directly applicable to beams in a non-harmonic potential. A new scheme has been developed in which the decay time of a higher than zeroth order transverse head-tail mode may be estimated by taking into account the synchrotron tune spread generated by the harmonic cavity potential. This scheme is presented along with the results of numerical simulations performed in order to confirm the analytical predictions and justify the assumptions made. The extension of the scheme to more complex scenarios is also discussed.

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Chapter in Book/Report/Conference proceeding
publication status
published
subject
in
6th International Particle Accelerator Conference, IPAC 2015
pages
4 pages
publisher
Joint Accelerator Conferences Website (JACoW)
conference name
6th International Particle Accelerator Conference, IPAC 2015
external identifiers
  • scopus:84994608041
ISBN
9783954501687
language
English
LU publication?
yes
id
1a6f1859-edd5-457f-9fb3-15215f6c9f7f
date added to LUP
2017-02-16 14:38:27
date last changed
2017-04-02 04:35:14
@inproceedings{1a6f1859-edd5-457f-9fb3-15215f6c9f7f,
  abstract     = {<p>At nonzero chromaticity, the threshold current due to transverse coupled bunch instabilities in an electron storage ring is defined by intrabunch head-tail motion of higher than zeroth order. Multibunch tracking simulations predict that this threshold can be increased to several times its original value through the introduction of bunch lengthening harmonic cavities. One previously suggested explanation is the narrower spectra of the elongated bunches but reliable estimates for the threshold currents are not obtainable for anything other than rigid beam motion since the usual Sacherer formalism is not directly applicable to beams in a non-harmonic potential. A new scheme has been developed in which the decay time of a higher than zeroth order transverse head-tail mode may be estimated by taking into account the synchrotron tune spread generated by the harmonic cavity potential. This scheme is presented along with the results of numerical simulations performed in order to confirm the analytical predictions and justify the assumptions made. The extension of the scheme to more complex scenarios is also discussed.</p>},
  author       = {Cullinan, F. J. and Nagaoka, Ryutaro and Skripka, G. and Fernandes Tavares, Pedro},
  booktitle    = {6th International Particle Accelerator Conference, IPAC 2015},
  isbn         = {9783954501687},
  language     = {eng},
  pages        = {102--105},
  publisher    = {Joint Accelerator Conferences Website (JACoW)},
  title        = {The damping of transverse coherent instabilities by harmonic cavities},
  year         = {2015},
}