An Impartial Perspective for Superconducting Nb3Sn coated Copper RF Cavities for Future Accelerators

TL;DR

This paper advocates for R&D in superconducting Nb3Sn coated copper RF cavities as a cost-effective alternative to bulk niobium, highlighting potential benefits for future accelerators like the ILC and Muon Collider.

Contribution

It emphasizes the importance of developing Nb3Sn coatings on inexpensive metals and explores the parallel-feed RF structure concept to improve accelerator affordability.

Findings

Nb3Sn coatings on copper show promise for RF cavities.

Parallel-feed RF structures could enhance accelerator design.

Current efforts are progressing despite limited funding.

Abstract

This Snowmass21 Contributed Paper encourages the Particle Physics community in fostering R&D in Superconducting Nb3Sn coated Copper RF Cavities instead of costly bulk Niobium. It describes the pressing need to devote effort in this direction, which would deliver higher gradient and higher temperature of operation and reduce the overall capital and operational costs of any future collider. It is unlikely that an ILC will be built in the next ten years with Nb as one of the main cost drivers of SRFs. This paper provides strong arguments on the benefits of using this time for R&D on producing Nb3Sn on inexpensive and thermally efficient metals such as Cu or bronze, while pursuing in parallel the novel U.S. concept of parallel-feed RF accelerator structures. A technology that synergistically uses both of these advanced tools would make an ILC or equivalent machines more affordable and more likely to be built. Such a successful enterprise would readily apply to other HEP accelerators, for instance a Muon Collider, and to accelerators beyond HEP. We present and assess current efforts in the U.S. on the novel concept of parallel-feed RF accelerator structures, and in the U.S. and abroad in producing Nb3Sn films on either Cu or bronze despite minimal funding.