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Title: Beam breakup instability studies of powerful energy recovery linac for experiments

Journal Article · · Physical Review Accelerators and Beams

The maximum achievable beam current in an energy recovery linac (ERL) is often constrained by beam breakup (BBU) instability. Our previous research highlighted that filling patterns have a substantial impact on BBU instabilities in multipass ERLs. In this study, we extend our investigation to the eight-cavity model of the Powerful ERL for Experiment (PERLE). We evaluate its requirements for damping cavity higher order modes (HOMs) and propose optimal filling patterns and bunch timing strategies. Our findings reveal a significant new insight: while filling patterns are crucial, the timing of bunches also plays a critical role in mitigating HOM beam loading and BBU instability. This previously underestimated factor is essential for effective BBU control. We estimated the PERLE threshold current using both analytical and numerical models, incorporating the designed PERLE HOM dampers. During manufacturing, HOM frequencies are expected to vary slightly. Our study found no significant difference in BBU suppression for relative rms frequency jitters of 0.001, 0.002, and 0.005 for the same HOM. Introducing a jitter of 0.001 into our models, we found that the dampers effectively suppressed BBU instability, achieving a threshold current an order of magnitude higher than the design requirement. Our results offer new insights into ERL BBU beam dynamics and have important implications for the design of future ERLs. Published by the American Physical Society 2025

Research Organization:
Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Sponsoring Organization:
Science and Technology Facilities Council (STFC); USDOE Office of Science (SC), Nuclear Physics (NP)
Grant/Contract Number:
AC05-06OR23177
OSTI ID:
2505084
Report Number(s):
DOE/OR/23177-7611; JLAB-ACP--24-4159; 011003
Journal Information:
Physical Review Accelerators and Beams, Journal Name: Physical Review Accelerators and Beams Journal Issue: 1 Vol. 28; ISSN 2469-9888; ISSN PRABCJ
Publisher:
American Physical SocietyCopyright Statement
Country of Publication:
United States
Language:
English

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