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arXiv · 2405.18738

Coherent synchrotron radiation instability in low-emittance electron storage rings

Sara Dastan·Demin Zhou·Takuya Ishibashi·Emanuel Karantzoulis·Simone Di Mitri·Ryan Lindberg
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Abstract

Longitudinal impedances at high frequencies, which extend far beyond the width of the beam spectrum, can pose a threat to the performance of modern low-emittance electron storage rings, as they can establish a relatively low threshold for microwave instability. In such rings, coherent synchrotron radiation (CSR) emerges as a prominent contributor to these high-frequency impedances. This paper undertakes a systematic investigation into the effects of CSR on electron rings, utilizing Elettra 2.0, a ring of fourth-generation light sources, and the SuperKEKB low-energy ring, a ring of $e^+e^-$ circular colliders, as illustrative examples. Our work revisits theories of microwave instability driven by CSR impedance, extending the analysis to encompass other high-frequency impedances such as resistive wall and coherent wiggler radiation. Through instability analysis and numerical simulations conducted on the two aforementioned rings, the study explored the impact of high-frequency impedances and their interactions with broadband impedances from discontinuities in vacuum chambers.

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Sara Dastan, Demin Zhou, Takuya Ishibashi, Emanuel Karantzoulis, Simone Di Mitri, Ryan Lindberg. 2024-05-29. Coherent synchrotron radiation instability in low-emittance electron storage rings. https://arxiv.org/abs/2405.18738

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