Microwave instability threshold from coherent wiggler radiation impedance in storage rings
The contribution of coherent wiggler radiation (CWR) to the microwave instability threshold in wiggler-dominated storage rings such as damping rings for colliders is discussed in detail. Three different coherent wiggler radiation impedance models are considered: the free-space steady-state model, the parallel-plates shielding steady-state model, and the rectangular-chamber shielding model. The field dynamics of CWR are compared, showing that the broad-band unshielded CWR becomes dominated by resonant structures when chamber shielding is considered. To suppress the narrow-band impedance in damping wigglers with chamber shielding, we propose employing a detuned damping wiggler. A new, simple, analytical method of solving the dispersion relation and detecting the CWR-driven microwave instability threshold is presented. The theory is compared with the numerical simulations of a Vlasov-Fokker-Planck solver for the Electron Ion Collider backup storage ring cooler and confirms that the microwave instability threshold gets higher for negative momentum compaction.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- Grant/Contract Number:
- SC0012704; AC02-06CH11357
- OSTI ID:
- 1974097
- Alternate ID(s):
- OSTI ID: 1986055
- Report Number(s):
- BNL-224515-2023-JAAM; PRABCJ; 051002
- Journal Information:
- Physical Review Accelerators and Beams, Journal Name: Physical Review Accelerators and Beams Vol. 26 Journal Issue: 5; ISSN 2469-9888
- Publisher:
- American Physical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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