Novel "Hot-Bronze" Nb3Sn for Compact Accelerators

Published November 22, 2021

Bright field STEM cross-section images of Nb3Sn films produced using (a) the newly-discovered hot bronze method and (b) the post-reaction method.

A new "hot bronze" thin film growth recipe was developed to produce high quality superconducting Niobium-Tin (Nb₃Sn) films that are easier to fabricate and that outperform existing technologies.

What is the finding?

Nb₃Sn coated superconducting radiofrequency (SRF) cavities could potentially operate in the 4–8K temperature range reached by compact refrigerators, enabling small and even portable x-ray, and intense electron beam sources. Present Nb₃Sn cavity coating requires high temperatures, ~1200°C, eliminating the potential benefits of combining with a Cu cavity body.

Researchers at ASC-National MagLab developed a new ~700°C "hot bronze" Nb₃Sn coating recipe, scalable to cavity production, that can produce high quality Nb₃Sn films on bronze substrates.

Why is this important?

This new recipe can be scaled to produce Nb₃Sn surfaces inside copper shells to produce next-generation superconducting radio frequency (SRF) cavities. Such cavities will be able to operate at higher temperatures than the current state-of-the-art bulk niobium cavities, reducing capital and operational costs significantly, and paving the way to next generation of particle accelerators. Furthermore, the ability to operate at higher temperature – without the large and costly infrastructure required by superfluid helium – will enable future applications requiring compact, portable accelerators for industrial, medical, science, and environmental applications.

Who did the research?

Wenura Withanage¹, Andre Juliao^1,2, and Lance D. Cooley^1,2

¹Applied Superconductivity Center - National MagLab; ²Florida State University;

Why did this research need the MagLab?

The MagLab's Applied Superconductivity Center has long been a pioneer in advancing the synthesis and characterization of Nb₃Sn superconducting wires. This expertise was used to address challenges faced by SRF cavities. The experiments required the use of new thin-film deposition equipment at the MagLab that is tailored for the study of Nb and Nb₃Sn. The images in the Figure were taken using the state-of-the-art high-resolution electron microscopy facility at MagLab.