Multilayer coating for higher accelerating fields in superconducting radio-frequency cavities: a review of theoretical aspects

TL;DR

This paper reviews the theoretical principles behind multilayer superconducting coatings, focusing on their potential to enhance the accelerating fields in superconducting radio-frequency cavities by analyzing field limits, optimal layer configurations, and surface resistance.

Contribution

It provides a comprehensive review of the theoretical aspects of multilayer and bilayer superconducting structures for RF cavities, highlighting design parameters and limitations.

Findings

Analysis of the superconductor-insulator-superconductor (S-I-S) structure

Discussion of optimal layer thicknesses and material choices

Evaluation of surface resistance and field limits

Abstract

Theory of the superconductor-insulator-superconductor (S-I-S) multilayer structure in superconducting accelerating cavity application is reviewed. The theoretical field limit, optimum layer thicknesses and material combination, and surface resistance are discussed. Those for the S-S bilayer structure are also reviewed.