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Investigations of the surface resistance of superconducting materials

In particle accelerators superconducting RF cavities are widely used to achieve high accelerating gradients and low losses. Power consumption is proportional to the surface resistance RS which depends on a number of external parameters, including frequency, temperature, magnetic and electric field....

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Detalles Bibliográficos
Autor principal: Junginger, Tobias
Lenguaje:eng
Publicado: 2012
Materias:
Acceso en línea:https://dx.doi.org/10.11588/heidok.00013728
http://cds.cern.ch/record/1489972
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author Junginger, Tobias
author_facet Junginger, Tobias
author_sort Junginger, Tobias
collection CERN
description In particle accelerators superconducting RF cavities are widely used to achieve high accelerating gradients and low losses. Power consumption is proportional to the surface resistance RS which depends on a number of external parameters, including frequency, temperature, magnetic and electric field. Presently, there is no widely accepted model describing the increase of Rs with applied field. In the frame of this project the 400 MHz Quadrupole Resonator has been extended to 800 and 1200 MHz to study surface resistance and intrinsic critical RF magnetic field of superconducting samples over a wide parameter range, establishing it as a world-wide unique test facility for superconducting materials. Different samples were studied and it was shown that Rs is mainly caused by the RF electric field in the case of strongly oxidized surfaces. This can be explained by interface tunnel exchange of electrons between the superconductor and localized states in adjacent oxides. For well prepared surfaces, however, the majority of the dissipation is caused by the magnetic field and Rs factorizes into field and temperature dependent parts. These different loss mechanisms were correlated to surface topography of the samples and distribution of oxides by using ultrasonic force microscopy and X-ray photon spectroscopy.
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institution Organización Europea para la Investigación Nuclear
language eng
publishDate 2012
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spelling cern-14899722023-10-26T13:22:57Zdoi:10.11588/heidok.00013728http://cds.cern.ch/record/1489972engJunginger, TobiasInvestigations of the surface resistance of superconducting materialsAccelerators and Storage RingsIn particle accelerators superconducting RF cavities are widely used to achieve high accelerating gradients and low losses. Power consumption is proportional to the surface resistance RS which depends on a number of external parameters, including frequency, temperature, magnetic and electric field. Presently, there is no widely accepted model describing the increase of Rs with applied field. In the frame of this project the 400 MHz Quadrupole Resonator has been extended to 800 and 1200 MHz to study surface resistance and intrinsic critical RF magnetic field of superconducting samples over a wide parameter range, establishing it as a world-wide unique test facility for superconducting materials. Different samples were studied and it was shown that Rs is mainly caused by the RF electric field in the case of strongly oxidized surfaces. This can be explained by interface tunnel exchange of electrons between the superconductor and localized states in adjacent oxides. For well prepared surfaces, however, the majority of the dissipation is caused by the magnetic field and Rs factorizes into field and temperature dependent parts. These different loss mechanisms were correlated to surface topography of the samples and distribution of oxides by using ultrasonic force microscopy and X-ray photon spectroscopy.CERN-THESIS-2012-152oai:cds.cern.ch:14899722012-10-25T17:35:21Z
spellingShingle Accelerators and Storage Rings
Junginger, Tobias
Investigations of the surface resistance of superconducting materials
title Investigations of the surface resistance of superconducting materials
title_full Investigations of the surface resistance of superconducting materials
title_fullStr Investigations of the surface resistance of superconducting materials
title_full_unstemmed Investigations of the surface resistance of superconducting materials
title_short Investigations of the surface resistance of superconducting materials
title_sort investigations of the surface resistance of superconducting materials
topic Accelerators and Storage Rings
url https://dx.doi.org/10.11588/heidok.00013728
http://cds.cern.ch/record/1489972
work_keys_str_mv AT jungingertobias investigationsofthesurfaceresistanceofsuperconductingmaterials