Advances in Nb3Sn superconducting radiofrequency cavities towards first practical accelerator applications

Abstract

Nb3Sn is a promising next-generation material for superconducting radiofrequency cavities, with significant potential for both large scale and compact accelerator applications. However, so far, Nb3Sn cavities have been limited to cw accelerating fields <18 MV/m. In this paper, new results are presented with significantly higher fields, as high as 24 MV/m in single cell cavities. Results are also presented from the first ever Nb3Sn-coated 1.3 GHz 9-cell cavity, a full-scale demonstration on the cavity type used in production for the European XFEL and LCLS-II. Results are presented together with heat dissipation curves to emphasize the potential for industrial accelerator applications using cryocooler-based cooling systems. The cavities studied have an atypical shiny visual appearance, and microscopy studies of witness samples reveal significantly reduced surface roughness and smaller film thickness compared to typical Nb3Sn films for superconducting cavities. Possible mechanisms for increased maximum field are discussed as well as implications for physics of RF superconductivity in the low coherence length regime. Outlook for continued development is presented.

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Cited by in corpus (9)

• Detecting High-Frequency Gravitational Waves with Microwave Cavities
• Tuning microwave losses in superconducting resonators
• Smooth, homogeneous, high-purity Nb3Sn superconducting RF resonant cavity by seed-free electrochemical synthesis
• Thermodynamic route of Nb3Sn nucleation: Role of oxygen
• ZrNb(CO) RF superconducting thin film with high critical temperature in the theoretical limit
• A Time-Dependent Ginzburg-Landau Framework for Sample-Specific Simulation of Superconductors for SRF Applications
• Significant improvement of the lower critical field in Y doped Nb: potential replacement of basic material for the radio-frequency superconducting cavity
• Microscopic Investigation of rf Vortex Nucleation in Nb3Sn Films Using a Near-Field Magnetic Microwave Microscope
• Microwave Vortex Motion Characterization of Nb${}_3$Sn Coatings for Applications in High Magnetic Fields