SRF2023 - Table of Session: TUCBA (Fundamental R&D II)

Paper	Title	Page
TUCBA01	Measurements of the Amplitude-Dependent Microwave Surface Resistance of a Proximity-Coupled Au/Nb Bilayer	369
	T.E. Oseroff, M. Liepe, Z. Sun Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	A sample host cavity is used to measure the surface resistance of a niobium substrate with a gold film deposited in place of its surface oxide. This talk will report about this measurement result. The film thickness of the gold layer was increased from 0.1 nm to 2.0 nm in five steps to study the impact of the normal layer thickness. The 0.1 nm film was found to reduce the surface resistance below its value with the surface oxide present and to enhance the quench field. The magnitude of the surface resistance increased substantially with gold film thickness. The surface resistance field-dependence appeared to be independent from the normal layer thickness. The observations reported in this work have profound implications for both low-field and high-field S.C. microwave devices. By controlling or eliminating the niobium oxide using a gold layer to passivate the niobium surface, it may be possible to improve the performance of SRF cavities used for particle acceleration. This method to reduce surface oxidation while maintaining low surface resistance could also be relevant for minimizing dissipation due to two-level systems observed in low-field low-temperature devices.
	Slides TUCBA01 [2.292 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUCBA01
About •	Received ※ 19 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 26 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Measurements of the Amplitude-Dependent Microwave Surface Resistance of a Proximity-Coupled Au/Nb Bilayer

369

T.E. Oseroff, M. Liepe, Z. Sun
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

A sample host cavity is used to measure the surface resistance of a niobium substrate with a gold film deposited in place of its surface oxide. This talk will report about this measurement result. The film thickness of the gold layer was increased from 0.1 nm to 2.0 nm in five steps to study the impact of the normal layer thickness. The 0.1 nm film was found to reduce the surface resistance below its value with the surface oxide present and to enhance the quench field. The magnitude of the surface resistance increased substantially with gold film thickness. The surface resistance field-dependence appeared to be independent from the normal layer thickness. The observations reported in this work have profound implications for both low-field and high-field S.C. microwave devices. By controlling or eliminating the niobium oxide using a gold layer to passivate the niobium surface, it may be possible to improve the performance of SRF cavities used for particle acceleration. This method to reduce surface oxidation while maintaining low surface resistance could also be relevant for minimizing dissipation due to two-level systems observed in low-field low-temperature devices.

Slides TUCBA01 [2.292 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUCBA01

About •

Received ※ 19 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 26 July 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)