Filling Pattern Dependence of Regenerative Beam Breakup Instability in Energy Recovery Linacs

Abstract

Beam breakup instability is a potential issue for all particle accelerators and is often the limiting factor for the maximum beam current that can be achieved. This is particularly relevant for Energy Recovery Linacs with multiple passes where a relatively small amount of charge can result in a large beam current. Recent studies have shown that the choice of filling pattern and recirculation scheme for a multi-pass energy recovery linac can drastically affect the interactions between the beam and RF system. In this paper we further explore this topic to study how filling patterns affect the beam breakup instability and how this can allow us to optimise the design in order to minimise this effect. We present a theoretical model of the beam-RF interaction as well as numerical modeling and show that the threshold current can vary by factors of 2-4, and potentially even more depending on the machine design parameters. Therefore a judicious choice of filling pattern can greatly increase the onset of BBU, expanding the utility of future ERLs.

arXiv comment10 pages, 10 figures, submitted to Physical Review Accelerators and Beams on 27th, April, 2021

References in corpus (7)

• A Large Hadron Electron Collider at CERN: Report on the Physics and Design Concepts for Machine and Detector
• Beam-Breakup Instability Theory for Energy Recovery Linacs
• PERLE: Powerful Energy Recovery Linac for Experiments - Conceptual Design Report
• Future High Energy Circular e+e- Collider using Energy-Recovery Linacs
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Cited by in corpus (1)

• Construction of Self-Consistent Longitudinal Matches in Multi-Pass Energy Recovery Linacs