Determination of the magnetic field dependence of the surface resistance of superconductors from cavity tests

Delayen, Jean; Park, H.; Silva, S. U. De; Ciovati, Gianluigi; Li, Z.

doi:10.1103/physrevaccelbeams.21.122001

Cited by 6 publications

(2 citation statements)

References 26 publications

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“…Further details of the test setup and data processing, including accounting for the non-uniform field distribution across the surface (Delayen et al, 2018), are described in (Kolb et al, 2020). Measurements of Q 0 and B p are done in a zeroed external magnetic field using a set of Helmholtz coils which surround the cavity and cryostat.…”

Section: Methodsmentioning

confidence: 99%

Mid-T heat treatments on BCP’ed coaxial cavities at TRIUMF

Kolb,

Yao,

Blackburn

et al. 2023

Front. Electron. Mater

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Mid-T heat treatments in the range from 250°C to 400°C on superconducting radio-frequency (SRF) cavities have been shown to provide high quality factors that rise with applied rf field strength in high frequency, electro-polished (EP), elliptical cavities operating at 2 K, similar to nitrogen doped cavities. The rise in quality factor is attributed to a decrease in the temperature dependent part of the surface resistance RBCS. Until now, no results have been reported for these new treatments on quarter-wave resonators (QWR) and half-wave resonators (HWR). The TRIUMF multi-mode coaxial cavities are dedicated test cavities that allow frequency and temperature resolved performance characterization of treatments without changing environments, therefore providing an excellent test vehicle to test these new treatments with rf frequencies ranging from 200 to 1,200 MHz. In this paper, performance measurements from both QWR and HWR cavities are reported and their performance compared with four different treatments: baseline, a conventional 120°C low temperature bake for 48 h, and two mid-T bakes at 300°C and 400°C for 3 h. In addition, sample analysis using SEM, EDX and SIMS of witness samples is also shown. It is found that the mid-T bakes are not directly transferable to low frequency cavities. In the fundamental modes of the two test cavities, no performance gain over the baseline treatment nor a decreasing temperature dependent component with rising rf amplitude was observed. At frequencies above 1 GHz and low temperatures, the mid-T bakes show a reduced field dependence of RBCS compared to both the baseline and 120°C treatments.

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Section: Methodsmentioning

confidence: 99%

Mid-T heat treatments on BCP’ed coaxial cavities at TRIUMF

Kolb,

Yao,

Blackburn

et al. 2023

Front. Electron. Mater

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“…Several other models are reported in order to understand the microwave resistance in SRF cavities extending the theory to clean, dirty, equilibrium and non-equilibrium superconductors [143,144,145,146,147]. The nitrogen doping and infusion studies were also extended to different frequency cavities [148,149], showing that the frequency might play the role in the field dependence of microwave surface resistance [146].…”

Section: Figure 17mentioning

confidence: 99%

Nitrogen doping and infusion in SRF cavities: A review

Dhakal

2020

Physics Open

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Characterizing materials for superconducting radiofrequency applications—A comprehensive overview of the quadrupole resonator design and measurement capabilities

Keckert

Kleindienst

Kugeler

et al. 2021

Review of Scientific Instruments

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Test cavities to characterize superconductor samples are of great interest for the development of materials suitable for superconducting radio frequency (SRF) accelerator systems. They can be used to investigate fundamental SRF loss mechanisms and to study the material limitations for accelerator applications. Worldwide, this research is based on only few systems that differ in operating frequency, sample size and shape, and the accessible parameter space of frequency, temperature, and RF field strength. For useful performance predictions in future accelerators, it is important that the operating parameter range is close to that employed in accelerating systems. Since 2014, the Helmholtz-Zentrum Berlin has operated such a system built around a redesigned Quadrupole Resonator (QPR). It is based on a system originally developed at CERN. Important new design modifications were developed, along with new measurement techniques and insight into their limitations. In the meantime, an increasing number of laboratories are adopting the QPR for their measurement campaigns. This paper provides a comprehensive overview of the state-of-the-art, the wide spectrum of measurement capabilities, and a detailed analysis of measurement uncertainties, as well as the limitations one should be aware of to maximize the effectiveness of the system. In the process, we provide examples of measurements performed with Nb3Sn and bulk niobium.

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Determination of the magnetic field dependence of the surface resistance of superconductors from cavity tests

Cited by 6 publications

References 26 publications

Mid-T heat treatments on BCP’ed coaxial cavities at TRIUMF

Mid-T heat treatments on BCP’ed coaxial cavities at TRIUMF

Nitrogen doping and infusion in SRF cavities: A review

Characterizing materials for superconducting radiofrequency applications—A comprehensive overview of the quadrupole resonator design and measurement capabilities

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