Contribution to a conference proceedings

GSI-2025-00448

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Self-Consistent Long-Term Dynamics of Space Charge Driven Resonances in 2D and 3D

Oeftiger, A. (Corresponding author)GSI* ; Boine-Frankenheim, O. ; Hofmann, I.GSI* ; Gianfelice, E. (Editor) ; Nagaitsev, S. (Editor) ; Kim, D. E. (Editor) ; Marx, M. (Editor) ; Schaa, V. R. W. (Editor)

2021
JACoW Publishing Geneva, Switzerland

Please use a persistent id in citations: doi:10.18429/JACOW-HB2021-TUAC1  doi:10.15120/GSI-2025-00448

Abstract: Understanding the 3D collective long-term response of beams exposed to resonances is of theoretical interest and essential for advancing high intensity synchrotrons. This study of a hitherto unexplored beam dynamical regime is based on 2D and 3D self-consistent particle-in-cell simulations and on careful analysis using tune spectra and phase space. It shows that in Gaussian-like beams Landau damping suppresses all coherent parametric resonances, which are of higher than second order (the 'envelope instability'). Our 3D results are obtained in an exemplary stopband, which includes the second order coherent parametric resonance and a fourth order structural resonance. They show that slow synchrotron oscillation plays a significant role. Moreover, for the early time evolution of emittance growth the interplay of incoherent and coherent resonance response matters, and differentiation between halo and different core regions is essential. In the long-term behavior we identify a progressive, self-consistent drift of particles toward and across the resonance, which results in effective compression of the initial tune spectrum. However, no visible imprint of the coherent features is left over, which only control the picture during the first one or two synchrotron periods. An intensity limit criterion and an asymptotic formula for long-term rms emittance growth are suggested. Comparison with the commonly used non-self-consistent 'frozen space charge' model shows that in 3D this approximation yields a fast and useful orientation, but it is a conservative estimate of the tolerable intensity.

Keyword(s): Accelerator Physics ; Beam Dynamics in Rings

Note: Published by JACoW Publishing under the terms of the Creative Commons Attribution 3.0 International license.

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Contributing Institute(s):

1. Accelerator Physics (APH)

Research Program(s):

1. 899 - ohne Topic (POF4-899) (POF4-899)

Experiment(s):

1. no experiment theory work (theory)

Appears in the scientific report 2021

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Database coverage:
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