CERN Accelerating science

Article
Title	Progress and R/D challenges for FCC-ee SRF
Author(s)	Venturini Delsolaro, W (CERN) ; Garlasche, M (CERN) ; Peauger, F (CERN) ; Rosaz, G (CERN) ; Karpov, I (CERN) ; Zhang, L (Beijing, Inst. High Energy Phys.) ; Valente Feliciano, A M (Jefferson Lab) ; Udongwo, S A (Rostock U.) ; Bianchi, A (CERN) ; Bellini, G (CERN) ; Ferrera, L M A (CERN) ; Pereira Carlos, C (CERN) ; Vega Cid, L (CERN) ; Leith, S (CERN) ; Proslier, T (IRFU, Saclay, DACM) ; Gorgi Zadeh, S (CERN) ; Timmins, M (CERN) ; Therasse, M (CERN) ; Koettig, T (CERN) ; Atieh, S (CERN) ; Brunner, O (CERN) ; Gerigk, F (CERN)
Publication	2023
Number of pages	13
In:	EPJ Tech. Instrum. 10 (2023) 6
DOI	10.1140/epjti/s40485-023-00094-5
Subject category	Accelerators and Storage Rings
Study	CERN FCC
Abstract	The FCC-ee machines present a huge challenge for the RF systems, which need to be adapted to very diverse beam conditions going from moderate energy and high current for the Z machine to high energy and low beam current for the ttbar. This inverse scaling results naturally from a fixed budget for the synchrotron radiation, which the SRF cavities need to compensate. A global solution was elaborated for the FCC Conceptual Design Report (Abada in Eur Phys J Spec Top 228):261–623, 2019), and is referred here as the baseline. Recently, further studies have led to a new optimized baseline, still based on traditional elliptical cavities. In parallel, a novel concept, named the Slotted Waveguide ELLiptical (SWELL), was proposed with the potential of greatly simplified logistics and reduced costs. Under several aspects, all these changes call for enhanced performance of the RF systems. A vigorous R&D; program has therefore continued since the publication of the CDR, with the aim of pushing the performance and demonstrating the feasibility of a more advanced baseline and, more recently, of the SWELL option. The progress and challenges of this ambitious program were presented in the dedicated SRF sessions at FCC week 2022 (FCC week 2022 website, 2022, https://indico.cern.ch/event/1064327/timetable/) and are summarized in this paper.
Copyright/License	publication: © 2023-2024 The Author(s) (License: CC-BY-4.0)

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