References of "Lousberg, Grégory"
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See detailMagnetic properties of drilled bulk high-temperature superconductors filled with a ferromagnetic powder
Lousberg, Grégory; Fagnard, Jean-François ULiege; Chaud, Xavier et al

in Superconductor Science and Technology (2011), 24

It is shown that filling the holes of a drilled bulk high-temperature superconductor (HTS) with a soft ferromagnetic powder enhances its trapping properties. The magnetic properties of the trapped field ... [more ▼]

It is shown that filling the holes of a drilled bulk high-temperature superconductor (HTS) with a soft ferromagnetic powder enhances its trapping properties. The magnetic properties of the trapped field magnet are characterized by Hall probe mapping and magnetization measurements. This analysis is completed by a numerical model based on a 3D finite-element method where the conductivity of the superconducting material is described by a power law while the permeability of the ferromagnetic material is fixed to a given value and is considered uniform. Numerical results support the experimental observations. In particular, they confirm the increase of trapped flux that is observed with Hall probe mapping after impregnation. [less ▲]

Detailed reference viewed: 114 (43 ULiège)
See detailImproving the performance of trapped field magnets made of drilled bulk high-temperature superconductors by filling the holes with a soft ferromagnetic material.
Lousberg, Grégory; Fagnard, Jean-François ULiege; Ausloos, Marcel ULiege et al

Conference (2010, August)

The field trapped in a drilled bulk high-temperature superconductor (HTS) is shown to be enhanced when the holes are filled with a powder of a soft ferromagnetic material. Characterizations based on Hall ... [more ▼]

The field trapped in a drilled bulk high-temperature superconductor (HTS) is shown to be enhanced when the holes are filled with a powder of a soft ferromagnetic material. Characterizations based on Hall probe mapping and magnetization measurements are used and show an increase of the trapped magnetic field after impregnation. These results are examined with the help of a 3D finite element model, where the ferromagnet material has a simplified, linear, constitutive law in order to keep a manageable number of mesh nodes. Although such an approach is a first-order approximation, it already confirms the experimental observation and indicates a maximum increase of the magnetic flux of 40 %. [less ▲]

Detailed reference viewed: 9 (3 ULiège)
See detailModeling high-temperature superconductors containing an array of holes
Vanderheyden, Benoît ULiege; Lousberg, Grégory; Ausloos, Marcel ULiege et al

Conference (2010, May 07)

We have recently implemented a finite-element model for the penetration of the magnetic flux inside a bulk superconductor containing an array of holes (thin-wall superconductor), with the help of the open ... [more ▼]

We have recently implemented a finite-element model for the penetration of the magnetic flux inside a bulk superconductor containing an array of holes (thin-wall superconductor), with the help of the open-source code GetDp. In this talk, I introduce the A-phi formulation used, with edge elements and spanning tree gauges. I explain how a time-iterative method allows one to make calculations with fewer time steps, and compare the obtained results with those derived by the Brandt method. [less ▲]

Detailed reference viewed: 14 (1 ULiège)
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See detailDC and AC shielding properties of bulk high-Tc superconducting tubes
Fagnard, Jean-François ULiege; Denis, Samuel; Lousberg, Grégory et al

Poster (2008, August)

In this work we have studied numerically and experimentally the magnetic flux penetration in high-Tc superconducting tube subjected to a uniform magnetic field parallel to its long axis. This study is ... [more ▼]

In this work we have studied numerically and experimentally the magnetic flux penetration in high-Tc superconducting tube subjected to a uniform magnetic field parallel to its long axis. This study is carried in view of designing low-frequency magnetic shields by exploiting the diamagnetic properties of high-Tc superconducting ceramics. We have measured the field attenuation for DC and AC applied fields (40 Hz < f < 400 Hz) and we have confronted data with computer modeling of the field distribution in the hollow of the tube. The numerical model is based on an algorithm proposed by Brandt (Phys. Rev. B 58, 6506, 1998). We have studied the spatial variation of the shielding factor (ratio between the external applied field and the internal applied field) along the axis of the tube. The agreement between experimental and simulated data was found to be very satisfactory. The data enabled us to distinguish between two penetration routes for the magnetic flux: (i) from the external surface of the tube (ii) and from the opening ends. We have also determined the phase shift between the internal and the applied field. Finally, we have studied the frequency dependence of the AC magnetic shielding factor. The shielding factor was found to exhibit a power law which can be explained quantitatively from scaling laws arising from the E = Ec(J/Jc)^n dependence. [less ▲]

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See detailMeasurement and modeling of macroscopic ferromagnetic/high-Tc superconductor hybrid structures: applications to drilled bulk HTS with ferromagnetic materials inserted inside the holes.
Lousberg, Gregory; Regnier, J.-H.; Ausloos, M et al

Poster (2008, August)

Hybrid ferromagnetic/high-Tc superconductors (F/S) structures are realized by inserting iron cylinders inside the macroscopic columnar holes of drilled bulk high-Tc superconductors. The ferromagnetic ... [more ▼]

Hybrid ferromagnetic/high-Tc superconductors (F/S) structures are realized by inserting iron cylinders inside the macroscopic columnar holes of drilled bulk high-Tc superconductors. The ferromagnetic material, with its tendency to concentrate the magnetic flux lines, modifies the magnetic properties of HTS that are characterized by a repulsion of the flux lines. In particular, the trapped field distribution of hybrid F/S results from a trade-off between the opposite magnetic properties of both materials. With the help of a 3-axis Hall probe mapping experiment, we characterize both vertical and transverse components of the trapped magnetic field. The distribution of the magnetic field trapped in the neighborhood of a hole inside which a ferromagnetic material is inserted is further investigated by high-resolution magneto-optic images. Experimental results are discussed with the help of a 3D finite-element model of hybrid F/S structure. [less ▲]

Detailed reference viewed: 23 (6 ULiège)