Impedance modelling and collective effects in the Future Circular e+e− Collider with 4 IPs

The FCC-ee impedance model is being constantly updated closely following the vacuum chamber design and parameters evolution. In particular, at present, a thicker NEG coating of 150 nm (instead of previous 100 nm) has been suggested by the vacuum experts, and a more realistic impedance model of the b...

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Bibliographic Details
Published in:EPJ techniques and instrumentation 2022-08, Vol.9 (1), p.1-19, Article 10
Main Authors: Migliorati, M., Antuono, C., Carideo, E., Zhang, Y., Zobov, M.
Format: Article
Language:English
Subjects:
Accelerating the design of the future circular collider
Atomic
Beam interactions
Bellows
Biological and Medical Physics
Biomaterials
Biophysics
Characterization and Evaluation of Materials
Design parameters
Feasibility studies
Impedance
Mathematical models
Measurement Science and Instrumentation
Molecular
Optical and Plasma Physics
Particle physics
Physics
Physics and Astronomy
Research Article
Simulation
Spectroscopy and Microscopy
Vacuum chambers
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Summary:The FCC-ee impedance model is being constantly updated closely following the vacuum chamber design and parameters evolution. In particular, at present, a thicker NEG coating of 150 nm (instead of previous 100 nm) has been suggested by the vacuum experts, and a more realistic impedance model of the bellows has been investigated. Moreover, also the transverse impedance has been updated by considering the same sources as for the longitudinal case. Therefore, the FCC-ee impedance database is getting more complete and the impedance model is being refined. In this paper we describe the presently available machine coupling impedance in both longitudinal and transverse planes, and study the impedance-driven single bunch instabilities (with and without beam-beam interaction) for the new FCC-ee parameter set with 4 interaction points (IPs). The results are compared with the previously obtained ones and a further possible mitigation of the beam-beam head-tail instability (X-Z instability) is proposed.
ISSN:2195-7045
2195-7045
DOI:10.1140/epjti/s40485-022-00084-z