Harmonic-cavity stabilization of longitudinal coupled-bunch instabilities with a nonuniform fill
(2020) In Physical Review Accelerators and Beams 23(7).- Abstract
In synchrotrons, nonuniform fill patterns, which give rise to beam phase transients and a spread in synchrotron tune between bunches, have been observed to damp longitudinal coupled-bunch instabilities driven by higher-order modes in rf cavities. The transients are especially large in the presence of Landau cavities, which are used commonly in storage-ring light sources and particularly in the new generation of diffraction-limited storage rings. A method has recently been devised to predict the beam transient including complex form factors for the different bunches. This has now been extended to accurately predict the growth-rates and oscillation frequencies of coupled-bunch modes for arbitrary fill patterns, taking the individual... (More)
In synchrotrons, nonuniform fill patterns, which give rise to beam phase transients and a spread in synchrotron tune between bunches, have been observed to damp longitudinal coupled-bunch instabilities driven by higher-order modes in rf cavities. The transients are especially large in the presence of Landau cavities, which are used commonly in storage-ring light sources and particularly in the new generation of diffraction-limited storage rings. A method has recently been devised to predict the beam transient including complex form factors for the different bunches. This has now been extended to accurately predict the growth-rates and oscillation frequencies of coupled-bunch modes for arbitrary fill patterns, taking the individual complex form factors and equilibrium phases of the different bunches into account. In this paper, the extended method is presented and the theory is outlined. For a case with significant transient beam loading, predictions of the resulting beam transient and bunch profiles are compared to measurements. Predictions of coupled-bunch mode behavior are then benchmarked against results from the macroparticle tracking code mbtrack with good agreement. Finally, the method is used to predict the behavior of coupled-bunch modes as a function of the fields in passive Landau cavities.
(Less)
- author
- Cullinan, F. J. LU ; Andersson, A. LU and Tavares, P. F. LU
- organization
- publishing date
- 2020-02
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Physical Review Accelerators and Beams
- volume
- 23
- issue
- 7
- article number
- 074402
- publisher
- American Physical Society
- external identifiers
-
- scopus:85101141524
- ISSN
- 2469-9888
- DOI
- 10.1103/PHYSREVACCELBEAMS.23.074402
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © 2020 authors. Published by the American Physical Society.
- id
- 27dc3baf-caa8-4823-914b-89f07c59b51a
- date added to LUP
- 2022-03-31 13:39:03
- date last changed
- 2022-04-23 23:09:48
@article{27dc3baf-caa8-4823-914b-89f07c59b51a,
abstract = {{<p>In synchrotrons, nonuniform fill patterns, which give rise to beam phase transients and a spread in synchrotron tune between bunches, have been observed to damp longitudinal coupled-bunch instabilities driven by higher-order modes in rf cavities. The transients are especially large in the presence of Landau cavities, which are used commonly in storage-ring light sources and particularly in the new generation of diffraction-limited storage rings. A method has recently been devised to predict the beam transient including complex form factors for the different bunches. This has now been extended to accurately predict the growth-rates and oscillation frequencies of coupled-bunch modes for arbitrary fill patterns, taking the individual complex form factors and equilibrium phases of the different bunches into account. In this paper, the extended method is presented and the theory is outlined. For a case with significant transient beam loading, predictions of the resulting beam transient and bunch profiles are compared to measurements. Predictions of coupled-bunch mode behavior are then benchmarked against results from the macroparticle tracking code mbtrack with good agreement. Finally, the method is used to predict the behavior of coupled-bunch modes as a function of the fields in passive Landau cavities.</p>}},
author = {{Cullinan, F. J. and Andersson, A. and Tavares, P. F.}},
issn = {{2469-9888}},
language = {{eng}},
number = {{7}},
publisher = {{American Physical Society}},
series = {{Physical Review Accelerators and Beams}},
title = {{Harmonic-cavity stabilization of longitudinal coupled-bunch instabilities with a nonuniform fill}},
url = {{http://dx.doi.org/10.1103/PHYSREVACCELBEAMS.23.074402}},
doi = {{10.1103/PHYSREVACCELBEAMS.23.074402}},
volume = {{23}},
year = {{2020}},
}