How to Achieve the Best SRF Performance: (Practical) Limitations and Possible Solutions

TL;DR

This paper reviews the physical limitations of superconducting radio frequency (SRF) cavities, especially Niobium ones, and discusses practical surface preparation techniques and models to push their performance beyond current limits.

Contribution

It provides a comprehensive overview of surface preparation requirements, physical limitations, and potential solutions to enhance SRF cavity performance, including overcoming material monopolies.

Findings

Surface cleanliness and damage critically affect SRF performance.

Models suggest fundamental limits are linked to surface properties.

Proposed solutions may enable higher SRF cavity performance.

Abstract

This tutorial presents in the first part the requirement for the surface preparation of RF Niobium cavities and its justification in term s of physical origin of limitation (e.g. cleanliness and field emission, influence of the surface treatments, morphology and surface damage, etc.). in the second part we discuss the different models describing the ultimate limits of SRF cavities, and present one of the possible ways to overcome Niobium monopoly toward higher performances.