Thallium-based high-temperature superconductors for beam impedance mitigation in the Future Circular Collider. (8th June 2017)

• Record Type: Journal Article
• Authors: Calatroni, S; Bellingeri, E; Ferdeghini, C; Putti, M; Vaglio, R; Baumgartner, T; Eisterer, M
• Is Part Of: Superconductor science & technology. Volume 30:Number 7(2017:Jul.)
• Publication Date: 2017-06-08
• Subjects: FCC -- beam screen -- HTS coating -- thallium -- Tl-1223; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/1361-6668/aa6bd0
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: CERN has recently started a design study for a possible next-generation high-energy hadron–hadron collider (Future Circular Collider—FCC-hh). The FCC-hh study calls for an unprecedented center-of-mass collision energy of 100 TeV, achievable by colliding counter-rotating proton beams with an energy of 50 TeV steered in a 100 km circumference tunnel by superconducting magnets which produce a dipole field of 16 T. The beams emit synchrotron radiation at high power levels, which, to optimize cryogenic efficiency, is absorbed by a beam-facing screen, coated with copper, and held at 50 K in the current design. The surface impedance of this screen has a strong impact on beam stability, and copper at 50 K allows for a limited beam stability margin only. This motivates the exploration of whether high-temperature superconductors (HTS), the only known materials possibly having a surface impedance lower than copper under the required operating conditions, would represent a viable alternative. This paper summarizes the FCC-hh requirements and focuses on identifying the best possible HTS material for this purpose. It reviews in particular the properties of Tl-based HTS, and discusses the consequent motivation for developing a deposition process for such compounds, which should be scalable to the size of the FCC components.