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https://doi.org/10.18429/JACoW-IPAC2019-MOPGW088
Title A Two-Mode Model to Study the Effect of Space Charge on TMCI in the "Long-Bunch" Regime
Authors
  • E. Métral
    CERN, Geneva, Switzerland
Abstract Using a two-mode approach for the Transverse Mode-Coupling Instability (TMCI) in the ’short-bunch’ regime (where the mode-coupling takes place between the modes 0 and -1, such as in the CERN LHC), both a reactive damper (ReaD) and Space Charge (SC) are expected to be beneficial: the ReaD would shift the mode 0 up while SC would shift the mode -1 down, but in both cases the coupling (and related instability) would occur at higher intensities. However, the situation is more involved in the ’long-bunch’ regime (where the mode-coupling takes place between higher-order modes, such as in the CERN SPS). As the ReaD modifies only the (main) mode 0 and not the others, it is expected to have no effect for the main mode-coupling. As concerns SC, it modifies all the modes except the mode 0, and the result has been a subject of discussion for two decades. A two-mode approach is discussed in detail in this contribution for the case of a single bunch interacting with a broad-band resonator impedance in the ’long-bunch’ regime. This model reveals in particular that in the presence of space charge, the intensity threshold can only be similar to or lower than that in the absence of space charge.
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Conference IPAC2019
Series International Particle Accelerator Conference (10th)
Location Melbourne, Australia
Date 19-24 May 2019
Publisher JACoW Publishing, Geneva, Switzerland
Editorial Board Mark Boland (UoM, Saskatoon, SK, Canada); Hitoshi Tanaka (KEK, Tsukuba, Japan); David Button (ANSTO, Kirrawee, NSW, Australia); Rohan Dowd (ANSTO, Kirrawee, NSW, Australia); Volker RW Schaa (GSI, Darmstadt, Germany); Eugene Tan (ANSTO, Kirrawee, NSW, Australia)
Online ISBN 978-3-95450-208-0
Received 23 April 2019
Accepted 23 May 2019
Issue Date 21 June 2019
DOI doi:10.18429/JACoW-IPAC2019-MOPGW088
Pages 316-319
Copyright
Creative Commons CC logoPublished by JACoW Publishing under the terms of the Creative Commons Attribution 3.0 International license. Any further distribution of this work must maintain attribution to the author(s), the published article's title, publisher, and DOI.