scholarly journals A magneto-optical study on magnetic flux expulsion and pinning in high-purity niobium

2017 ◽  
Vol 122 (17) ◽  
pp. 173901 ◽  
Author(s):  
J. Köszegi ◽  
O. Kugeler ◽  
D. Abou-Ras ◽  
J. Knobloch ◽  
R. Schäfer
Keyword(s):  
Magnetic Flux ◽  
High Purity ◽  
Optical Study ◽  
Flux Expulsion

Magneto-Optical Study High-Purity Niobium for Superconducting RF Application

2011 ◽  
Author(s):  
A. A. Polyanskii ◽  
P. J. Lee ◽  
A. Gurevich ◽  
Zu-Hawn Sung ◽  
D. C. Larbalestier
Keyword(s):  
High Purity ◽  
Optical Study ◽  
Superconducting Rf

Electron Optical Study of Oxidation of High Purity Iron At Low Oxygen Pressures

JOM ◽  
1954 ◽  
Vol 6 (9) ◽  
pp. 1027-1035 ◽  
Author(s):  
Earl A. Guibransen ◽  
William R. McMillan ◽  
Kenneth F. Andrew
Keyword(s):  
High Purity ◽  
Optical Study ◽  
Low Oxygen ◽  
Purity Iron ◽  
High Purity Iron

Flux Jumps in Nb3Sn Superconducting Ribbon

1974 ◽  
Vol 52 (12) ◽  
pp. 1107-1109 ◽  
Author(s):  
R. B. Harrison ◽  
L. S. Wright
Keyword(s):  
Magnetic Flux ◽  
Normal Metal ◽  
Optical Study ◽  
Magnetic Stability ◽  
Flux Jumps

A magneto-optical study of the flux jumping behavior of samples of vapor deposited Nb3Sn ribbons has been undertaken. Observations have confirmed that the magnetic stability of the superconductor is greatly enhanced by the addition of normal metal claddings; this is demonstrated with tracings taken from photographs which show directly the magnetic flux patterns in the samples.

scholarly journals MAGNETIC FLUX EXPULSION IN STAR FORMATION

2011 ◽  
Vol 742 (1) ◽  
pp. 10 ◽  
Author(s):  
Bo Zhao ◽  
Zhi-Yun Li ◽  
Fumitaka Nakamura ◽  
Ruben Krasnopolsky ◽  
Hsien Shang
Keyword(s):  
Star Formation ◽  
Magnetic Flux ◽  
Flux Expulsion

scholarly journals Magneto-optical study of magnetic-flux penetration into a current-carrying high-temperature-superconductor strip

1999 ◽  
Vol 59 (14) ◽  
pp. 9655-9664 ◽  
Author(s):  
M. E. Gaevski ◽  
A. V. Bobyl ◽  
D. V. Shantsev ◽  
Y. M. Galperin ◽  
T. H. Johansen ◽  
...  
Keyword(s):  
High Temperature ◽  
Magnetic Flux ◽  
High Temperature Superconductor ◽  
Optical Study ◽  
Flux Penetration ◽  
A Current

Static field homogeneity artifacts due to magnetic flux expulsion by HTS coils for high-resolution magnetic resonance imaging

2020 ◽  
Vol 117 (25) ◽  
pp. 254101
Author(s):  
Aimé Labbé ◽  
Rose-Marie Dubuisson ◽  
Jean-Christophe Ginefri ◽  
Cornelis J. van der Beek ◽  
Luc Darrasse ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Magnetic Flux ◽  
Static Field ◽  
Resonance Imaging ◽  
Field Homogeneity ◽  
Flux Expulsion

scholarly journals Imprint of magnetic flux expulsion at the core–mantle boundary on geomagnetic field intensity variations

2020 ◽  
Vol 221 (3) ◽  
pp. 1984-2009 ◽  
Author(s):  
M Troyano ◽  
A Fournier ◽  
Y Gallet ◽  
C C Finlay
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Field Intensity ◽  
Geomagnetic Field ◽  
Western Europe ◽  
Vertical Component ◽  
Core Mantle Boundary ◽  
The Core ◽  
Flux Expulsion ◽  
Upper Boundary

SUMMARY During the last decade, rapid or extreme geomagnetic field intensity variations associated with rates greater than the maximum currently observed have been inferred from archeomagnetic data in the Near-East and in Western Europe. The most extreme events, termed geomagnetic spikes, are defined as intensity peaks occurring over a short time (a few decades), and are characterized by high variation rates, up to several μT yr–1. Magnetic flux expulsion from the Earth’s outer core has been suggested as one possible explanation for these peaks but has not yet been examined in detail. In this study, we develop a 2-D kinematic model for magnetic flux expulsion whose key control parameter is the magnetic Reynolds number Rm, the ratio of magnetic diffusion time to advection time. This model enables the tracking of magnetic field lines which are distorted and folded by a fixed flow pattern. Two processes govern the magnetic evolution of the system. The first is the expulsion of magnetic flux from closed streamlines, whereby flux gradually concentrates near the boundaries of the domain, which leads to an increase of the magnetic energy of the system. If the upper boundary separates the conducting fluid from an insulating medium, a second process then takes place, that of diffusion through this interface, which we can quantify by monitoring the evolution of the vertical component of magnetic induction along this boundary. It is the conjunction of these two processes that defines our model of magnetic flux expulsion through the core–mantle boundary. We analyse several configurations with varying flow patterns and magnetic boundary conditions. We first focus on flux expulsion from a single eddy. Since this specific configuration has been widely studied, we use it to benchmark our implementation against analytic solutions and previously published numerical results. We next turn our attention to a configuration which involves two counter-rotating eddies producing an upwelling at the centre of the domain, and comprises an upper boundary with an insulating medium. We find that the characteristic rise time and maximum instantaneous variation rate of the vertical component of the magnetic field that escapes the domain scale like $\sim R_m^{0.15}$ and $\sim R_m^{0.45}$, respectively. Extrapolation of these scaling laws to the Earth’s régime is compared with various purported archeointensity highs reported in the Near-East and in Western Europe. According to our numerical experiments magnetic flux expulsion is unlikely to produce geomagnetic spikes, while intensity peaks of longer duration (one century and more) and smaller variation rates appear to be compatible with this process.

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