Superconductors in realistic geometries: geometric edge barrier versus pinning

Brandt, Ernst Helmut

doi:10.1016/s0921-4534(99)00651-6

Cited by 38 publications

(34 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In all measurements the external magnetic fields (dc and ac) are carefully aligned parallel to the symmetry axis of the cylinders, so that above H c2 surface superconductivity can only nucleate on the cylindrical walls and not on the end faces. The demagnetization factor N Z = 0.36 derived from the initial slope of the dc magnetization curve M (H) = −H/(1−N Z ) agrees with the theoretical expression N Z = 1−1/(1+qa/b) [20].…”

Section: Methodssupporting

confidence: 84%

Surface superconductivity in niobium for superconducting RF cavities

Casalbuoni

Knabbe²,

Kötzler

et al. 2005

Nuclear Instruments and Methods in Physics Research Section A:

View full text Add to dashboard Cite

A systematic study is presented on the superconductivity (sc) parameters of the ultrapure niobium used for the fabrication of the nine-cell 1.3 GHz cavities for the linear collider project TESLA. Cylindrical Nb samples have been subjected to the same surface treatments that are applied to the TESLA cavities: buffered chemical polishing (BCP), electrolytic polishing (EP), low-temperature bakeout (LTB). The magnetization curves and the complex magnetic susceptibility have been measured over a wide range of temperatures and dc magnetic fields, and also for different frequencies of the applied ac magnetic field. The bulk superconductivity parameters such as the critical temperature T c = 9.26 K and the upper critical field B c2 (0) = 410 mT are found to be in good agreement with previous data. Evidence for surface superconductivity at fields above B c2 is found in all samples. The critical surface field exceeds the Ginzburg-Landau field B c3 = 1.695B c2 by about 10% in BCP-treated samples and increases even further if EP or LTB are applied. From the field dependence of the susceptibility and a power-law analysis of the complex ac conductivity and resistivity the existence of two different phases of surface superconductivity can be established which resemble the Meissner and Abrikosov phases in the bulk: (1) "coherent surface superconductivity", allowing sc shielding currents flowing around the entire cylindrical sample, for external fields B in the range B c2 < B < B coh c3 , and (2) "incoherent surface superconductivity" with disconnected sc domains for B coh c3 < B < B c3 . The "coherent" critical surface field separating the two phases is found to be B coh c3 = 0.81 B c3 for all samples. The exponents in the power law analysis are different for BCP and EP samples, pointing to different surface topologies.

show abstract

Section: Methodssupporting

confidence: 84%

Surface superconductivity in niobium for superconducting RF cavities

Casalbuoni

Knabbe²,

Kötzler

et al. 2005

Nuclear Instruments and Methods in Physics Research Section A:

View full text Add to dashboard Cite

show abstract

“…Other methods, therefore, would require high precision measurements to obtain a reasonable error for Hc1. This results are in according to the border and thickness effects and border magnetization that have been already described by other authors in an uniform magnetic field ( Brandt, 2000;Morozov et al, 1996;Li et al, 2004;Schmidt et al, 1997): 6. Example of application -permanent magnet over a superconducting torus…”

Section: Limits Of Applicationsupporting

confidence: 86%

Foundations of Meissner superconductor magnet mechanismus engineering

Pérez-Díaz¹,

Díez-Jiménez²

2011

Superconductivity - Theory and Applications

View full text Add to dashboard Cite

“…The proposed vector potential gauge can also be used for the calculation of the magnetic response of type-II superconductors in realistic geometries [24] under the influence of the edge barrier.…”

Section: Discussionmentioning

confidence: 99%

Vector potential gauge for superconducting regular polygons

Chibotaru

Ceulemans

Teniers

et al. 2002

The European Physical Journal B - Condensed Matter

View full text Add to dashboard Cite

Abstract. An approach to the Ginzburg-Landau problem of superconducting polygons is developed, based on the exact fulfillment of superconducting boundary conditions along the boundary of the sample. To this end an analytical gauge transformation for the vector potential A is found which gives An = 0 for the normal component along the boundary line of an arbitrary regular polygon. The use of the new gauge reduces the Ginzburg-Landau problem of superconducting polygons in external magnetic fields to an eigenvalue problem in a basis set of functions obeying Neumann boundary conditions. The advantages of this approach, especially for low magnetic fields, are illustrated and novel vortex patterns are obtained which can be probed experimentally.

show abstract

Superconductors in realistic geometries: geometric edge barrier versus pinning

Cited by 38 publications

References 29 publications

Surface superconductivity in niobium for superconducting RF cavities

Surface superconductivity in niobium for superconducting RF cavities

Foundations of Meissner superconductor magnet mechanismus engineering

Vector potential gauge for superconducting regular polygons

Contact Info

Product

Resources

About