Low temperature laser scanning microscopy of a superconducting radio-frequency cavity

Ciovati, Gianluigi; Anlage, Steven M.; Baldwin, Christopher L.; Cheng, Guanglei; Flood, R.; Jordan, Kevin; Kneisel, P.; Morrone, Michael; Nemeş, George; Turlington, L.; Wang, H.; Wilson, Katherine; Zhang, S.

doi:10.1063/1.3694570

Cited by 13 publications

(18 citation statements)

References 26 publications

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“…4. The cavity was then re-tested with a temperature mapping array installed around the cavity [17]. The Q0 vs Eacc curve was similar, and the cavity was limited again at low gradients due to a strong slope.…”

Section: Rf Test Resultsmentioning

confidence: 99%

Analysis of RF losses and material characterization of samples removed from a Nb₃Sn-coated superconducting RF cavity

Pudasaini¹,

Eremeev

Reece

et al. 2020

Supercond. Sci. Technol.

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Nb3Sn (Tc ≈ 18 K and Hsh ≈ 400 mT) is a prospective material to replace Nb (Tc ≈ 9 K and Hsh ≈ 200 mT) in SRF accelerator cavities for significant cost reduction and performance enhancement. Because of its material properties, Nb3Sn is best employed as a thin film (coating) inside an already built RF cavity structure. A particular test cavity noted as C3C4 was a 1.5 GHz single-cell Nb cavity, coated with Nb3Sn using Sn vapor diffusion process at Jefferson Lab. Cold measurements of the coated cavity indicated the superconducting transition temperature of about 18 K. Subsequent RF measurements indicated fielddependent surface resistance both at 4.3 K and 2.0 K. After initial cold measurements, the cavity RF loss distribution was studied with a thermometry mapping system. Loss regions were identified with thermometry and were cut out for material analysis. The presence of significantly thin patchy regions and other carbonrich defects is associated with strong local field-dependent surface resistance. This paper summarizes RF and thermometry results correlated with material science findings.

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Section: Rf Test Resultsmentioning

confidence: 99%

Analysis of RF losses and material characterization of samples removed from a Nb₃Sn-coated superconducting RF cavity

Pudasaini¹,

Eremeev

Reece

et al. 2020

Supercond. Sci. Technol.

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“…These defects induce PR hotspots which dominate the entire PR image and make it difficult to deduce the gap symmetry from the image. This drawback is demonstrated in Fig.3(c) and in other papers that discuss this issue 22,24,25 . In fact, many of the newly emerged unconventional superconductors of interest are very vulnerable to this defect issue during the lithographic process due to their sensitivity to solvents, water, and the ambient atmosphere.…”

Section: Principle Of the Experimentsmentioning

confidence: 76%

Dielectric resonator method for determining gap symmetry of superconductors through anisotropic nonlinear Meissner effect

Bae

Tan

Zhuravel

et al. 2019

Review of Scientific Instruments

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TechniqueAdvantages Disadvantages ARPES 4 Directly image band structure and gap ∆(k) Requires very pristine surfaces, finite energy resolution SQUID 8Sensitive to the sign change of the gap ∆(k) Requires high-quality tunnel junctions ARSH 6Relatively simple thermodynamic measurement Depends on the presence of magnetic vortices Interpretation is dependent on knowledge of Fermi surface details Raman 3Able to choose specific symmetries under test by choosing polarization orientationsRequires detailed theoretical calculations of response functions for each polarization orientation to interpret data aNLME [13][14][15][16] Directly image gap nodal structure in real-space, not sensitive to near-surface qualityRequires high-Q resonance with circulating currents over a single-domain sample.

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“…This widely used technique is called temperature mapping or simply T-mapping [3]. In order to gain direct information about the temperature distribution on the inner cavity surface JLab has developed a laser beam scanning apparatus [14]. This laser beam not only allows measurement of the surface temperature but can also be used to move vortex hot spots.…”

Section: Other Methods To Measure Losses Of Superconductors Under Rfmentioning

confidence: 99%

Devices for SRF material characterization

Goudket

Junginger

Xiao

2016

Supercond. Sci. Technol.

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The surface resistance Rs of superconducting materials can be obtained by measuring the quality factor of an elliptical cavity excited in a transverse magnetic mode (TM010). The value obtained has however to be taken as averaged over the whole surface. A more convenient way to obtain Rs, especially of materials which are not yet technologically ready for cavity production, is to measure small samples instead. These can be easily manufactured at low cost, duplicated and placed in film deposition and surface analytical tools. A commonly used design for a device to measure Rs consists of a cylindrical cavity excited in a transverse electric (TE110) mode with the sample under test serving as one replaceable endplate. Such a cavity has two drawbacks. For reasonably small samples the resonant frequency will be larger than frequencies of interest concerning SRF application and it requires a reference sample of known Rs. In this article we review several devices which have been designed to overcome these limitations, reaching sub-nΩ resolution in some cases. Some of these devices also comprise a parameter space in frequency and temperature which is inaccessible to standard cavity tests, making them ideal tools to test theoretical surface resistance models.

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Low temperature laser scanning microscopy of a superconducting radio-frequency cavity

Cited by 13 publications

References 26 publications

Analysis of RF losses and material characterization of samples removed from a Nb₃Sn-coated superconducting RF cavity

Analysis of RF losses and material characterization of samples removed from a Nb₃Sn-coated superconducting RF cavity

Dielectric resonator method for determining gap symmetry of superconductors through anisotropic nonlinear Meissner effect

Devices for SRF material characterization

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Low temperature laser scanning microscopy of a superconducting radio-frequency cavity

Cited by 13 publications

References 26 publications

Analysis of RF losses and material characterization of samples removed from a Nb3Sn-coated superconducting RF cavity

Analysis of RF losses and material characterization of samples removed from a Nb3Sn-coated superconducting RF cavity

Dielectric resonator method for determining gap symmetry of superconductors through anisotropic nonlinear Meissner effect

Devices for SRF material characterization

Contact Info

Product

Resources

About

Analysis of RF losses and material characterization of samples removed from a Nb₃Sn-coated superconducting RF cavity

Analysis of RF losses and material characterization of samples removed from a Nb₃Sn-coated superconducting RF cavity