Harmonic cavities and the transverse mode-coupling instability driven by a resistive wall

Journal Article · Wed Feb 14 00:00:00 EST 2018 · Physical Review Accelerators and Beams

DOI:https://doi.org/10.1103/PhysRevAccelBeams.21.024402· OSTI ID:1420491

Venturini, M.

The effect of rf harmonic cavities on the transverse mode-coupling instability (TMCI) is still not very well understood. We offer a fresh perspective on the problem by proposing a new numerical method for mode analysis and investigating a regime of potential interest to the new generation of light sources where resistive wall is the dominant source of transverse impedance. When the harmonic cavities are tuned for maximum flattening of the bunch profile we demonstrate that at vanishing chromaticities the transverse single-bunch motion is unstable at any current, with growth rate that in the relevant range scales as the 6th power of the current. With these assumptions and radiation damping included, we find that for machine parameters typical of 4th-generation light sources the presence of harmonic cavities could reduce the instability current threshold by more than a factor two.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1420491
• Alternate ID(s): OSTI ID: 1434020
• Journal Information: Physical Review Accelerators and Beams, Journal Name: Physical Review Accelerators and Beams Vol. 21 Journal Issue: 2; ISSN 2469-9888
• Publisher: American Physical Society
• Country of Publication: United States
• Language: English

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