Magnetic flux penetration; Superconductor films; Defects; Magnetic avalanches
Abstract :
[en] We consider the penetration of magnetic flux perpendicular to a Nb superconducting film containing edge indentations and/or defects. The presence of such defects and indented edges forces the induced currents to change direction abruptly, which gives rise to discontinuity lines (d-lines). It has been recently shown, by magneto-optical means, that the shape of the d-lines contain information about the size and the shape of the indentations [1]. Moreover, in contrast with what is commonly assumed, thermomagnetic instabilities are not preferentially triggered near the manufactured indentations, but rather along smooth edges [1]. Such phenomena can lead to unexpected quenching of superconducting samples and considerably damage them, which must be avoided in applications. In this poster, we investigate whether inhomogeneous superconducting properties can be responsible for triggering magnetic flux avalanches. To this aim, we numerically model the flux penetration and determine the distribution of current lines and electric fields for a situation where the superconducting properties vary locally over a small region of the film. We consider the variation of the thickness of the film, the critical current density and the size of the discontinuity. The resulting shapes of the d-lines are deduced and compared to analytical critical state approximations. We also determine the location and the amplitude of the maximal electric field in the film and compare it to typical values which must be reached in order to trigger magnetic flux avalanches. We conclude that the investigated variations lead to levels of electric field which are of the same order of magnitude as those generated by artificial indentations.
Disciplines :
Electrical & electronics engineering
Author, co-author :
Burger, Loïc ; Université de Liège - ULiège > Dép. d'électric., électron. et informat. (Inst.Montefiore) > Electronique et microsystèmes
Avila Osses, Jonathan ; Université de Liège - ULiège > Département de physique > Physique expérimentale des matériaux nanostructurés
Nguyen, Ngoc Duy ; Université de Liège - ULiège > Département de physique > Physique des solides, interfaces et nanostructures
Silhanek, Alejandro ; Université de Liège - ULiège > Département de physique > Physique expérimentale des matériaux nanostructurés
Vanderheyden, Benoît ; Université de Liège - ULiège > Dép. d'électric., électron. et informat. (Inst.Montefiore) > Electronique et microsystèmes
Language :
English
Title :
Influence of the inhomogeneous properties of a superconducting film on the penetration of the magnetic flux
Publication date :
20 September 2017
Number of pages :
A0
Event name :
EUCAS 2017, 13th European Conference on Applied Superconductivity
Event organizer :
The European Society for Applied Superconductivity (ESAS)
Event place :
Genève, Switzerland
Event date :
from September 17, 2017 to September 21, 2017
Audience :
International
Name of the research project :
ARC 13/18-08
Funders :
FWB - Fédération Wallonie-Bruxelles
Commentary :
References : [ 1 ] J. Brisbois et. al., Phys. Rev. B. 93 (2016) 054521.
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