Suppressed Superconductivity on the Surface of Superconducting RF Quality Niobium for Particle Accelerating Cavities
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States)
Significant performance degradation of superconducting RF (radio frequency) niobium cavities in high RF field is strongly associated with the breakdown of superconductivity on localized multi-scale surface defects lying within the 40 nm penetration depth. These defects may be on the nanometer scale, like grain boundaries and dislocations or even at the much larger scale of surface roughness and welding pits. By combining multiple superconducting characterization techniques including magneto-optical (MO) imaging and direct transport measurement with non-contact characterization of the surface topology using scanning confocal microscopy, we were able to show clear evidence of suppression of surface superconductivity at chemically treated RF-quality niobium. We found that pinning of vortices along GBs is weaker than pinning of vortices in the grains, which may indicate suppressed superfluid density on GBs. We also directly measured the local magnetic characteristics of BCP-treated Nb sample surface using a micro-Hall sensor in order to further understanding of the effect of surface topological features on the breakdown of superconducting state in RF mode.
- OSTI ID:
- 21516669
- Journal Information:
- AIP Conference Proceedings, Vol. 1352, Issue 1; Conference: 1. international symposium on the superconducting science and technology of ingot niobium, Newport News, VA (United States), 22-24 Sep 2010; Other Information: DOI: 10.1063/1.3580640; (c) 2011 American Institute of Physics; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CRYSTAL DEFECTS
DISLOCATIONS
GRAIN BOUNDARIES
NIOBIUM
PENETRATION DEPTH
POLISHING
RADIOWAVE RADIATION
RF SYSTEMS
ROUGHNESS
SENSORS
SPECTROSCOPY
SUPERCONDUCTIVITY
SUPERCONDUCTORS
SUPERFLUIDITY
SURFACES
WELDING
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
ELEMENTS
FABRICATION
JOINING
LINE DEFECTS
METALS
MICROSTRUCTURE
PHYSICAL PROPERTIES
RADIATIONS
REFRACTORY METALS
SURFACE FINISHING
SURFACE PROPERTIES
TRANSITION ELEMENTS