SRF2023 - List of Authors (Saribal, C.)

Paper	Title	Page
MOPMB017	Development of a Thermal Conductance Instrument for Niobium at Cryogenic Temperatures	109
	C. Saribal, C. Martens University of Hamburg, Hamburg, Germany W. Hillert, M. Wenskat University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Funding: University of Hamburg Particle accelerators form an important tool in a variety of research fields. In an effort to reduce operation costs while maintaining high energies, their accelerating structures are steadily improved towards higher accelerating fields and lower RF losses. Stable operation of such a cavity generally requires Joule-heating, generated in its walls, to be conducted to an outer helium bath. Therefore, it is of interest to experimentally evaluate how present and future cavity treatments affect thermal characteristics. We present an instrument for measuring the thermal performance of SRF cavity materials at cryogenic temperatures. Pairs of niobium disks are placed inside of a liquid helium bath and a temperature gradient is generated across them to obtain total thermal resistance for temperatures below 2 Kelvin. To get an idea of the instruments sensitivity and how standard cavity treatments influence thermal resistance, samples are tested post fabrication, polishing and 800 °C baking. The first tests show the commissioning of our newly set up system and if it is feasible to observe relevant changes and evaluate new and promising cavity treatments such as SIS structures.
	Poster MOPMB017 [3.217 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB017
About •	Received ※ 17 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 01 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WECBA01	Successful SIS Multilayer Activities on Cavities and Samples Using ALD
	I. González Díaz-Palacio, R.H. Blick, C. Saribal, R. Zierold University of Hamburg, Hamburg, Germany G.K. Deyu, W. Hillert, M. Wenskat University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Theoretically SIS multilayers predict to delay vortex penetration allowing for operation gradients more than the double of bulk Nb cavities and Q-values two orders of magnitude above. The University of Hamburg focuses on Atomic Layer Deposition (ALD) as most promising coating technique. In a proof-of principle experiment thermal ALD of Al₂O₃ was successfully applied to two 1.3GHz single-cell cavities achieving gradients above 40MV/m without any deterioration in Q-value [1]. Studies using plasma-enhanced ALD (PEALD) on planar samples focus on AlN and NbTiN as dielectric and superconductor material, respectively. The deposition process and post-deposition treatments have been optimized by studying the superconducting properties in magneto-transport and in vibrating sample magnetometry of the films. Different compositions, thicknesses, and thermal annealing treatments have been investigated with respect to their resistance, magnetization, flux trapping efficiency, thermal conductance, elemental composition, and crystallinity. Within this presentation, the aggregated results of all those measurements will be presented and discussed in detail. [1] Marc Wenskat et al 2023 Supercond. Sci. Technol. 36 015010
	Slides WECBA01 [4.209 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Development of a Thermal Conductance Instrument for Niobium at Cryogenic Temperatures

109

C. Saribal, C. Martens
University of Hamburg, Hamburg, Germany
W. Hillert, M. Wenskat
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Funding: University of Hamburg
Particle accelerators form an important tool in a variety of research fields. In an effort to reduce operation costs while maintaining high energies, their accelerating structures are steadily improved towards higher accelerating fields and lower RF losses. Stable operation of such a cavity generally requires Joule-heating, generated in its walls, to be conducted to an outer helium bath. Therefore, it is of interest to experimentally evaluate how present and future cavity treatments affect thermal characteristics. We present an instrument for measuring the thermal performance of SRF cavity materials at cryogenic temperatures. Pairs of niobium disks are placed inside of a liquid helium bath and a temperature gradient is generated across them to obtain total thermal resistance for temperatures below 2 Kelvin. To get an idea of the instruments sensitivity and how standard cavity treatments influence thermal resistance, samples are tested post fabrication, polishing and 800 °C baking. The first tests show the commissioning of our newly set up system and if it is feasible to observe relevant changes and evaluate new and promising cavity treatments such as SIS structures.

Poster MOPMB017 [3.217 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB017

About •

Received ※ 17 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 01 July 2023

Cite •

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

WECBA01

Successful SIS Multilayer Activities on Cavities and Samples Using ALD

I. González Díaz-Palacio, R.H. Blick, C. Saribal, R. Zierold
University of Hamburg, Hamburg, Germany
G.K. Deyu, W. Hillert, M. Wenskat
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Theoretically SIS multilayers predict to delay vortex penetration allowing for operation gradients more than the double of bulk Nb cavities and Q-values two orders of magnitude above. The University of Hamburg focuses on Atomic Layer Deposition (ALD) as most promising coating technique. In a proof-of principle experiment thermal ALD of Al₂O₃ was successfully applied to two 1.3GHz single-cell cavities achieving gradients above 40MV/m without any deterioration in Q-value [1]. Studies using plasma-enhanced ALD (PEALD) on planar samples focus on AlN and NbTiN as dielectric and superconductor material, respectively. The deposition process and post-deposition treatments have been optimized by studying the superconducting properties in magneto-transport and in vibrating sample magnetometry of the films. Different compositions, thicknesses, and thermal annealing treatments have been investigated with respect to their resistance, magnetization, flux trapping efficiency, thermal conductance, elemental composition, and crystallinity. Within this presentation, the aggregated results of all those measurements will be presented and discussed in detail.
[1] Marc Wenskat et al 2023 Supercond. Sci. Technol. 36 015010

Slides WECBA01 [4.209 MB]

Cite •

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