Nb₃Sn multicell cavity coating system at Jefferson Lab.

Area of Science:

• Materials Science
• Accelerator Physics
• Superconductivity

Background:

• Superconducting radio frequency niobium cavities are crucial for modern particle accelerators.
• Enhancing cavity performance (lower resistance, higher fields, higher temperatures) is key for future scientific and industrial applications.

Purpose of the Study:

• To design and evaluate a novel coating system for creating niobium-tin (Nb3Sn) films on the inner surfaces of niobium cavities.
• To assess the impact of Nb3Sn coatings on the radio frequency properties of accelerator cavities.

Main Methods:

• A niobium retort was used to heat niobium cavities via radiation.
• The niobium surface was exposed to tin (Sn) and tin(II) chloride (SnCl2) vapor during a heat cycle to form a ~2 μm Nb3Sn film.
• Characterization of film composition, structure, and radio frequency performance.

Main Results:

• Successful fabrication of a ~2 μm thick Nb3Sn film on the inner surface of niobium cavities.
• Demonstrated the feasibility of the coating system for both research and development (R&D) and practical accelerator cavities.
• Radio frequency properties of coated cavities were evaluated.

Conclusions:

• The developed Nb3Sn coating system offers a promising method for enhancing superconducting radio frequency cavities.
• This technology could lead to improved performance in scientific accelerators and cost-effective industrial solutions.