Author: Argyropoulos, T.
Paper Title Page
MOP16 New Analytical Criteria for Loss of Landau Damping in Longitudinal Plane 100
  • I. Karpov, T. Argyropoulos, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
  • S. Nese
    University of Bergen, Bergen, Norway
  Landau damping is a very important stabilization mechanism of beams in circular hadron accelerators. In the longitudinal plane, Landau damping is lost when the coherent mode is outside of the incoherent synchrotron frequency spread. In this paper, the threshold for loss of Landau damping (LLD) for constant inductive impedance ImZ/k is derived using the Lebedev matrix equation (1968). The results are confirmed by direct numerical solutions of the Lebedev equation and using the Oide-Yokoya method (1990). For more realistic impedance models of the ring, new definitions of an effective impedance and the corresponding cutoff frequency are introduced which allow using the same analytic expression for the LLD threshold. We also demonstrate that this threshold is significantly overestimated by the Sacherer formalism based on the previous definition of an effective impedance using the eigenfunctions of the coherent modes.  
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About • Received ※ 16 October 2021 — Revised ※ 24 October 2021 — Accepted ※ 02 December 2021 — Issue date ※ 11 April 2022
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