References of "Vanderheyden, Benoît"
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See detailBulk melt-processed (RE)BCO superconductors subjected to AC fields in “parallel” and “crossed” direction, experiment and modelling
Vanderbemden, Philippe ULg; Fagnard, Jean-François ULg; Babu, N. H. et al

Conference (2010, November)

When bulk melt-processed (RE)BCO samples are used as permanent magnets in various engineering applications (e.g. rotating machines, magnetic bearings), they may experience transient or periodic variations ... [more ▼]

When bulk melt-processed (RE)BCO samples are used as permanent magnets in various engineering applications (e.g. rotating machines, magnetic bearings), they may experience transient or periodic variations of the applied magnetic field. In such a situation, the remnant magnetization of the sample is found to decrease in running operation, which is particularly inconvenient for the long-term reliability of the system. There are several possible causes for such a phenomenon. The first is the temperature increase resulting from the losses caused by the variable applied field, and may arise when the field is parallel to the main direction of the trapped flux. The second is caused by the component of the magnetic field perpendicular to the main direction of the trapped flux (“crossed field” configuration). In the present talk we review the relevant parameters which have a detrimental impact on the remnant magnetization in both cases. Modelling results are compared to experimental data obtained on bulk YBCO samples subjected to field oscillations of large amplitude. [less ▲]

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See detailSPICE-Circuit Simulation of the Electrical Response of a Semiconductor Membrane to a Single-Stranded DNA Translocating Through a Nanopore
Leroux, Amandine ULg; Destiné, Jacques ULg; Vanderheyden, Benoît ULg et al

in IEEE Transactiones on Nanotechnology (2010), 9(3), 322-329

In this paper, we describe a circuit-element model for the electric detection of biomolecules in translocation through a nanopore in a semiconductor-oxide-semiconductor (SOS) membrane. The biomolecules ... [more ▼]

In this paper, we describe a circuit-element model for the electric detection of biomolecules in translocation through a nanopore in a semiconductor-oxide-semiconductor (SOS) membrane. The biomolecules are simulated as a superposition of individual charges moving through the nanopore and inducing a charge variation on the membrane electrodes that is modeled as a current source. The SOS membrane is discretized into interconnected elementary circuit elements. The model is tested on the translocation of 11 base single-stranded C3AC7 DNA molecule, for which the electric signal shows good qualitative agreement with the multiscale device approach of Gracheva et al., while quantifying the low-pass filtering in the membrane. Overall, the model confirms the possibility of identifying the sequence of the DNA bases electrically. [less ▲]

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See detailNumerical Study of the Shielding properties of Macroscopic Hybrid Ferromagnetic/Superconductor Hollow Cylinders
Lousberg, Grégory ULg; Fagnard, Jean-François ULg; Ausloos, Marcel ULg et al

in IEEE Transactions on Applied Superconductivity (2010), 20(1), 33

We study the magnetic shielding properties of hybrid ferromagnetic/superconductor (F/S) structures consisting of two coaxial cylinders, with one of each material.We use an axisymmetric finite-element ... [more ▼]

We study the magnetic shielding properties of hybrid ferromagnetic/superconductor (F/S) structures consisting of two coaxial cylinders, with one of each material.We use an axisymmetric finite-element model in which the electrical properties of the superconducting tube are modeled by a nonlinear E-J power law with a magnetic-field-dependent critical current density whereas the magnetic properties of the ferromagnetic material take saturation into account. We study and compare the penetration of a uniform axial magnetic field in two cases: 1) a ferromagnetic tube placed inside a larger superconducting tube (Ferro-In configuration) and 2) a ferromagnetic tube placed outside the superconducting one (Ferro-Out configuration). In both cases, we assess how the ferromagnetic tube improves the shielding properties of the sole superconducting tube. The influence of the geometrical parameters of the ferromagnetic tube is also studied: It is shown that, upon an optimal choice of the geometrical parameters, the range of magnetic fields that are efficiently shielded by the hightemperature superconductor tube alone can be increased by a factor of up to 7 (2) in a Ferro-Out (Ferro-In) configuration. The optimal configuration uses a 1020 carbon steel with a thickness of 2 mm and a height that is half that of the superconducting cylinder (80 mm). [less ▲]

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See detailModification of the trapped field in bulk HTS as a result of the drilling of a pattern of artificial holes
Lousberg, G. P.; Fagnard, Jean-François ULg; Ausloos, Marcel ULg et al

in Journal of Physics: Conference Series (2010), 234

The trapped magnetic field is examined in bulk high-temperature superconductors that are artificially drilled along their c-axis. The influence of the hole pattern on the magnetization is studied and ... [more ▼]

The trapped magnetic field is examined in bulk high-temperature superconductors that are artificially drilled along their c-axis. The influence of the hole pattern on the magnetization is studied and compared by means of numerical models and Hall probe mapping techniques. To this aim, we consider two bulk YBCO samples with a rectangular cross-section that are drilled each by six holes arranged either on a rectangular lattice (sample I) or on a centered rectangular lattice (sample II). For the numerical analysis, three different models are considered for calculating the trapped flux: (i), a two-dimensional (2D) Bean model neglecting demagnetizing effects and flux creep, (ii), a 2D finite-element model neglecting demagnetizing effects but incorporating magnetic relaxation in the form of an E – J power law, and, (iii), a 3D finite element analysis that takes into account both the finite height of the sample and flux creep effects. For the experimental analysis, the trapped magnetic flux density is measured above the sample surface by Hall probe mapping performed before and after the drilling process. The maximum trapped flux density in the drilled samples is found to be smaller than that in the plain samples. The smallest magnetization drop is found for sample II, with the centered rectangular lattice. This result is confirmed by the numerical models. In each sample, the relative drops that are calculated independently with the three different models are in good agreement. As observed experimentally, the magnetization drop calculated in the sample II is the smallest one and its relative value is comparable to the measured one. By contrast, the measured magnetization drop in sample (1) is much larger than that predicted by the simulations, most likely because of a change of the microstructure during the drilling process. [less ▲]

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See detailUse of second generation coated conductors for efficient shielding of DC magnetic fields
Fagnard, Jean-Francois ULg; Dirickx, Michel; Levin, G. A. et al

in Journal of Applied Physics (2010), 108

This paper reports the results of an experimental investigation of the performance of two types of magnetic screens assembled from YBa2Cu3O7-d (YBCO) coated conductors. Since effective screening of the ... [more ▼]

This paper reports the results of an experimental investigation of the performance of two types of magnetic screens assembled from YBa2Cu3O7-d (YBCO) coated conductors. Since effective screening of the axial DC magnetic field requires the unimpeded flow of an azimuthal persistent current, we demonstrate a configuration of a screening shell made out of standard YBCO coated conductor capable to accomplish that. The screen allows the persistent current to flow in the predominantly azimuthal direction at a temperature of 77 K. The persistent screen, incorporating a single layer of superconducting film, can attenuate an external magnetic field of up to 5 mT by more than an order of magnitude. For comparison purposes, another type of screen which incorporates low critical temperature quasi-persistent joints was also built. The shielding technique we describe here appears to be especially promising for the realization of large scale high-Tc superconducting screens. [less ▲]

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See detailShielding efficiency and E(J) characteristics measured on large melt cast Bi-2212 hollow cylinders in axial magnetic fields
Fagnard, Jean-François ULg; Elschner, Steffen; Bock, Joachim et al

in Superconductor Science and Technology (2010), 23

We show that tubes of melt cast Bi-2212 used as current leads for LTS magnets can also act as efficient magnetic shields. The magnetic screening properties under an axial DC magnetic field are ... [more ▼]

We show that tubes of melt cast Bi-2212 used as current leads for LTS magnets can also act as efficient magnetic shields. The magnetic screening properties under an axial DC magnetic field are characterized at several temperatures below the liquid nitrogen temperature (77 K). Two main shielding properties are studied and compared with those of Bi-2223, a material that has been considered in the past for bulk magnetic shields. The first property is related to the maximum magnetic flux density that can be screened, Blim; it is defined as the applied magnetic flux density below which the field attenuation measured at the centre of the shield exceeds 1000. For a cylinder of Bi-2212 with a wall thickness of 5 mm and a large ratio of length over radius, Blim is evaluated to 1 T at T = 10 K. This value largely exceeds the Blim value measured at the same temperature on similar tubes of Bi-2223. The second shielding property that is characterized is the dependence of Blim with respect to variations of the sweep rate of the applied field, dBapp/dt. This dependence is interpreted in terms of the power law E = Ec(J/Jc)^n and allows us to determine the exponent n of this E(J) characteristics for Bi-2212. The characterization of the magnetic field relaxation involves very small values of the electric field. This gives us the opportunity to experimentally determine the E(J) law in an unexplored region of small electric fields. Combining these results with transport and AC shielding measurements, we construct a piecewise E(J) law that spans over 8 orders of magnitude of the electric field. [less ▲]

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See detailSelf-heating of bulk high temperature superconductors of finite height subjected to a large alternating magnetic field
Laurent, Philippe; Fagnard, Jean-François ULg; Hari Babu, N. et al

in Superconductor Science and Technology (2010), 23

In this work we study, both experimentally and numerically, the self-heating of a bulk, large YBCO pellet of aspect ratio (thickness / diameter) ~ 0.4 subjected to a large AC magnetic field. To ensure ... [more ▼]

In this work we study, both experimentally and numerically, the self-heating of a bulk, large YBCO pellet of aspect ratio (thickness / diameter) ~ 0.4 subjected to a large AC magnetic field. To ensure accurate temperature measurements, the sample was placed in an experimental vacuum chamber to achieve a small and reproducible heat transfer coefficient between the superconductor and the cryogenic fluid. The temperature was measured at several locations on the sample surface during the self-heating process. The experimentally determined temperature gradients are found to be very small in this arrangement (< 0.2 K across the radius of the superconductor). The time-dependence of the average temperature T(t) is found to agree well with a theoretical prediction based on the one-dimensional (1-D) Bean model, assuming a uniform temperature in the sample. A 2-D magneto-thermal model was also used to determine the space and time-dependent temperature distribution T(r, z, t) during the application of the AC field. The losses in the bulk pellet were determined using an algorithm based on the numerical method of Brandt, which was combined with a heat diffusion algorithm implemented using a finite-difference method. The model is shown to be able to reproduce the main trends of the observed temperature evolution of the bulk sample during a self-heating process. Finally, the 2-D model is used to study the effect of a non-uniform distribution of critical current density Jc(r, z) on the losses within the bulk superconductor. [less ▲]

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See detailPulsed-field magnetization of drilled bulk high-temperature superconductors: flux front propagation in the volume and on the surface
Lousberg, Grégory ULg; Fagnard, Jean-François ULg; Haanappel, Evert et al

in Superconductor Science and Technology (2009), (22), 125026

We present a method for characterizing the propagation of the magnetic flux in an artificially drilled bulk high-temperature superconductor (HTS) during pulsed-field magnetization. As the magnetic pulse ... [more ▼]

We present a method for characterizing the propagation of the magnetic flux in an artificially drilled bulk high-temperature superconductor (HTS) during pulsed-field magnetization. As the magnetic pulse penetrates the cylindrical sample, the magnetic flux density is measured simultaneously in 16 holes by means of microcoils that are placed across the median plane, i.e. at an equal distance from the top and bottom surfaces, and close to the surface of the sample. We discuss the time evolution of the magnetic flux density in the holes during a pulse and measure the time taken by the external magnetic flux to reach each hole. Our data show that the flux front moves faster in the median plane than on the surface when penetrating the sample edge; it then proceeds faster along the surface than in the bulk as it penetrates the sample further. Once the pulse is over, the trapped flux density inside the central hole is found to be about twice as large in the median plane as on the surface. This ratio is confirmed by modelling. [less ▲]

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See detailMagnetic shielding properties of high- Tc superconducting hollow cylinders: model combining experimental data for axial and transverse magnetic field configurations
Fagnard, Jean-François ULg; Dirickx, Michel; Ausloos, Marcel ULg et al

in Superconductor Science and Technology (2009), 22(10), 10500210

Magnetic shielding efficiency was measured on high- Tc superconducting hollow cylinders subjected to either an axial or a transverse magnetic field in a large range of field sweep rates, dBapp/dt. The ... [more ▼]

Magnetic shielding efficiency was measured on high- Tc superconducting hollow cylinders subjected to either an axial or a transverse magnetic field in a large range of field sweep rates, dBapp/dt. The behaviour of the superconductor was modelled in order to reproduce the main features of the field penetration curves by using a minimum number of free parameters suitable for both magnetic field orientations. The field penetration measurements were carried out on Pb-doped Bi-2223 tubes at 77 K by applying linearly increasing magnetic fields with a constant sweep rate ranging between 10 uT s[?]1 and 10 mT s[?]1 for both directions of the applied magnetic field. The experimental curves of the internal field versus the applied field, Bin(Bapp), show that, at a given sweep rate, the magnetic field for which the penetration occurs, Blim, is lower for the transverse configuration than for the axial configuration. A power law dependence with large exponent, n', is found between Blim and dBapp/dt. The values of n' are nearly the same for both configurations. We show that the main features of the curves Bin(Bapp) can be reproduced using a simple 2D model, based on the method of Brandt, involving a E(J) power law with an n-exponent and a field-dependent critical current density, Jc(B), (following the Kim model: Jc = Jc0(1+B/B1)[?]1). In particular, a linear relationship between the measured n'-exponents and the n-exponent of the E(J) power law is suggested by taking into account the field dependence of the critical current density. Differences between the axial and the transverse shielding properties can be simply attributed to demagnetizing fields. [less ▲]

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See detailDC and AC Shielding Properties of Bulk High-Tc Superconducting Tubes
Fagnard, Jean-François ULg; Denis, Samuel; Lousberg, Grégory ULg et al

in IEEE Transactions on Applied Superconductivity (2009), 19(3), 2905-2908

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 ... [more ▼]

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 applied magnetic fields in the frequency range 5 mHz-0.1 Hz by Hall probe measurements and at audio frequencies using a sensing coil. A simple 1D analysis using the Kim critical state model was found to be able to reproduce the experimental data satisfactorily. We have also determined the phase shift between the internal and the applied field both experimentally and numerically. Finally, we have studied the sweep rate dependence of the magnetic shielding properties, using data recorded either at several constant sweep rates dB/dt or at several AC fields of various amplitudes and frequencies. Both methods agree with each other and lead to a n -value of the E ~ J n law equal to ~ 40 at 77 K. [less ▲]

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See detailNumerical simulation of the magnetization of high-temperature superconductors: a 3D finite element method using a single time-step iteration
Lousberg, Grégory ULg; Ausloos, Marcel ULg; Geuzaine, Christophe ULg et al

in Superconductor Science and Technology (2009), 22

In this paper, we report progress towards a 3D finite element model for the magnetization of a high-temperature superconductor (HTS): we suggest a method that takes into account a power law conductivity ... [more ▼]

In this paper, we report progress towards a 3D finite element model for the magnetization of a high-temperature superconductor (HTS): we suggest a method that takes into account a power law conductivity and demagnetization effects, while neglecting the effects associated with currents that are not perpendicular to the local magnetic induction. We consider samples that are subjected to a uniform magnetic field varying linearly with time. Their magnetization is calculated by means of a weak formulation in the magnetostatic approximation of the Maxwell equations (A–φ formulation). An implicit method is used for the temporal resolution (backward Euler scheme) and is solved with the open source solver GetDP. Fixed point iterations are used to deal with the power law conductivity of HTS. The finite element formulation is validated for an HTS tube with large n value by comparing with results obtained with other well-established methods. We show that carrying out the calculations with a single time-step (as opposed to many small time-steps) produces results with excellent accuracy in a drastically reduced simulation time. The numerical method is extended to the study of the trapped magnetization of cylinders that are drilled with different arrays of columnar holes arranged parallel to the cylinder axis. [less ▲]

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See detailMeasurement of the magnetic field inside the holes of a drilled bulk high-Tc superconductor
Lousberg, Grégory ULg; Fagnard, Jean-François ULg; Noudem, Jacques G et al

in Superconductor Science and Technology (2009), 22

We use macroscopic holes drilled in a bulk YBCO superconductor to probe its magnetic properties in the volume of the sample. The sample is subjected to an AC magnetic flux with a density ranging from 30 ... [more ▼]

We use macroscopic holes drilled in a bulk YBCO superconductor to probe its magnetic properties in the volume of the sample. The sample is subjected to an AC magnetic flux with a density ranging from 30 to 130 mT and the flux in the superconductor is probed by miniature coils inserted in the holes. In a given hole, three different penetration regimes can be observed: (i) the shielded regime, where no magnetic flux threads the hole; (ii) the gradual penetration regime, where the waveform of the magnetic field has a clipped sine shape whose fundamental component scales with the applied field; and (iii) the flux concentration regime, where the waveform of the magnetic field is nearly a sine wave, with an amplitude exceeding that of the applied field by up to a factor of two. The distribution of the penetration regimes in the holes is compared with that of the magnetic flux density at the top and bottom surfaces of the sample, and is interpreted with the help of optical polarized light micrographs of these surfaces. We show that the measurement of the magnetic field inside the holes can be used as a local characterization of the bulk magnetic properties of the sample. [less ▲]

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See detailRandom matrix model for antiferromagnetism and superconductivity on a two-dimensional lattice
Vanderheyden, Benoît ULg; Jackson, A. D.

in Physical Review B (Condensed Matter and Materials Physics) (2009), 79(14), 144502

We suggest a new mean-field method for studying the thermodynamic competition between magnetic and superconducting phases in a two-dimensional square lattice. A partition function is constructed by ... [more ▼]

We suggest a new mean-field method for studying the thermodynamic competition between magnetic and superconducting phases in a two-dimensional square lattice. A partition function is constructed by writing microscopic interactions that describe the exchange of density and spin fluctuations. A block structure dictated by spin, time-reversal, and bipartite symmetries is imposed on the single-particle Hamiltonian. The detailed dynamics of the interactions are neglected and replaced by a normal distribution of random matrix elements. The resulting partition function can be calculated exactly. The thermodynamic potential has a structure which depends only on the spectrum of quasiparticles propagating in fixed condensation fields, with coupling constants that can be related directly to the variances of the microscopic processes. The resulting phase diagram reveals a fixed number of phase topologies whose realizations depend on a single coupling parameter ratio, alpha. Most phase topologies are realized for a broad range of values of alpha and can thus be considered robust with respect to moderate variations in the detailed description of the underlying interactions. [less ▲]

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See detailBulk high-Tc superconductors with drilled holes: how to arrange the holes to maximize the trapped magnetic flux?
Lousberg, Grégory ULg; Ausloos, Marcel ULg; Vanderbemden, Philippe ULg et al

in Superconductor Science and Technology (2008), 21

Drilling holes in a bulk high-Tc superconductor enhances the oxygen annealing and the heat exchange with the cooling liquid. However, drilling holes also reduces the amount of magnetic flux that can be ... [more ▼]

Drilling holes in a bulk high-Tc superconductor enhances the oxygen annealing and the heat exchange with the cooling liquid. However, drilling holes also reduces the amount of magnetic flux that can be trapped in the sample. In this paper, we use the Bean model to study the magnetization and the current line distribution in drilled samples, as a function of the hole positions. A single hole perturbs the critical current flow over an extended region that is bounded by a discontinuity line, where the direction of the current density changes abruptly. We demonstrate that the trapped magnetic flux is maximized if the centre of each hole is positioned on one of the discontinuity lines produced by the neighbouring holes. For a cylindrical sample, we construct a polar triangular hole pattern that exploits this principle; in such a lattice, the trapped field is ∼20% higher than in a squared lattice, for which the holes do not lie on discontinuity lines. This result indicates that one can simultaneously enhance the oxygen annealing, the heat transfer and maximize the trapped field. [less ▲]

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See detailAn ac susceptometer for the characterization of large, bulk superconducting samples
Laurent, Philippe ULg; Fagnard, Jean-François ULg; Vanderheyden, Benoît ULg et al

in Measurement Science & Technology (2008), 19(8), 085705

The main purpose of this work was to design, develop and construct a simple, low-cost ac susceptometer to measure large, bulk superconducting samples (up to 32 mm in diameter) in the temperature range ... [more ▼]

The main purpose of this work was to design, develop and construct a simple, low-cost ac susceptometer to measure large, bulk superconducting samples (up to 32 mm in diameter) in the temperature range 78–120 K. The design incorporates a double heating system that enables a high heating rate (25 K h−1) while maintaining a small temperature gradient (<0.2 K) across the sample. The apparatus can be calibrated precisely using a copper coil connected in series with the primary coil. The system has been used successfully to measure the temperature dependence of the ac magnetic properties of entire RE–Ba–Cu–O [(RE)BCO] bulk superconducting domains. A typical ac susceptibility measurement run from 78 K to 95 K takes about 2 h, with excellent temperature resolution (temperature step ∼ 4 mK) around the critical temperature, in particular. [less ▲]

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See detailSimulation of the highly non linear properties of bulk superconductors: finite element approach with a backwardmethod and a single time step
Lousberg, G.; Ausloos, Marcel ULg; Geuzaine, Christophe ULg et al

in Proceedings of the fourth international conference on advanced computational methods in engineering, ACOMEN 2008 (2008)

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See detailMagnetic shielding properties of high-temperature superconducting tubes subjected to axial fields
Denis, Samuel ULg; Dusoulier, Laurent; Dirickx, Michel ULg et al

in Superconductor Science and Technology (2007), 20(3), 192-201

We have experimentally studied the magnetic shielding properties of a cylindrical shell of BiPbSrCaCuO subjected to low frequency AC axial magnetic fields. The magnetic response has been investigated as a ... [more ▼]

We have experimentally studied the magnetic shielding properties of a cylindrical shell of BiPbSrCaCuO subjected to low frequency AC axial magnetic fields. The magnetic response has been investigated as a function of the dimensions of the tube, the magnitude of the applied field and the frequency. These results are explained quantitatively by employing the method of Brandt ( 1998 Phys. Rev. B 58 6506) with a Jc( B) law appropriate for a polycrystalline material. Specifically, we observe that the applied field can sweep into the central region either through the thickness of the shield or through the opening ends, the latter mechanism being suppressed for long tubes. For the first time, we systematically detail the spatial variation of the shielding factor ( the ratio of the applied field over the internal magnetic field) along the axis of a high-temperature superconducting tube. The shielding factor is shown to be constant in a region around the centre of the tube, and to decrease as an exponential in the vicinity of the ends. This spatial dependence comes from the competition between two mechanisms of field penetration. The frequency dependence of the shielding factor is also discussed and shown to follow a power law arising from the finite creep exponent n. [less ▲]

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See detailField penetration into hard type-II superconducting tubes: effects of a cap, a non-superconducting joint, and non-uniform superconducting properties
Denis, Samuel ULg; Dirickx, Michel ULg; Vanderbemden, Philippe ULg et al

in Superconductor Science and Technology (2007), 20(5), 418-427

Using the numerical method of Brandt (1998 Phys. Rev. B 58 6506), we study the penetration of a uniform magnetic field that is gradually applied parallel to the axis of finite type-II superconducting ... [more ▼]

Using the numerical method of Brandt (1998 Phys. Rev. B 58 6506), we study the penetration of a uniform magnetic field that is gradually applied parallel to the axis of finite type-II superconducting tubular samples with strong pinning. This study is carried out in view of designing low-frequency magnetic shields by exploiting the diamagnetic properties of type-II superconductors. First, we compare the field penetration into open and closed tubes. For long tubes (length larger than three times the outer diameter), we show that a cap weakly affects the maximum magnetic induction that can be shielded, but greatly increases the region over which the field is nearly uniform. When the length of the tube is shorter, both the maximum shieldable magnetic induction and the uniformity of the field attenuation are enhanced by closing the tube. We also show that making a hole in the cap, which is often necessary for applications, does not greatly affect the shielding properties provided the diameter of the hole is small compared to that of the tube (hole diameter smaller than a quarter of the outer tube diameter). In view of designing large size magnetic shields, superconducting tubes of finite size need to be joined together. We therefore examine in a second part how the presence of a non-superconducting joint between the tubes affects the shielding efficiency. It is shown that the effect of a joint depends upon its position along the tube axis and strongly increases with its size. Third, we study how non-uniform superconducting properties affect the shielding capabilities. [less ▲]

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See detailCharacterisation of the magnetic shielding properties of YBaCuO thick films prepared by electrophoretic deposition on silver substrates
Denis, Samuel; Grenci, G.; Dusoulier, Laurent et al

in Journal of Physics: Conference Series (2006), 43

This communication reports experimental results on the superconducting properties of YBaCuO thick films prepared by electrophoretic deposition on silver substrates. The magnetic shielding properties of ... [more ▼]

This communication reports experimental results on the superconducting properties of YBaCuO thick films prepared by electrophoretic deposition on silver substrates. The magnetic shielding properties of the coatings were characterised by various methods. First, the electrical resistance and the transport critical current density, Jc, were determined. Our coatings exhibit a superconducting transition at a temperature of 90 K. Next, shielding characterisations were carried out at 77 K for samples having either a slab or a cylindrical geometry. In both cases, the frequency of the applied magnetic field was 103 Hz; the field behind the shielding wall was measured by a pick-up coil connected to a lock-in amplifier. In the case of cylindrical samples and for an applied induction lower than 1 G, the field inside the shielding enclosure is reduced by a factor greater than 106 (i.e. 120 dB) with respect to the applied field. [less ▲]

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See detailYBa2Cu3O(7-delta) thick films on Ag prepared by the electrophoretic deposition technique
Dusoulier, Laurent; Denis, Samuel; Fagnard, Jean-François ULg et al

in Journal of Physics: Conference Series (2006), 43

YBa2Cu3O7-δ thick films have been deposited onto Ag substrates by the Electrophoretic Deposition (EPD) technique. Different microstructures and electrical behaviours were observed depending on the ... [more ▼]

YBa2Cu3O7-δ thick films have been deposited onto Ag substrates by the Electrophoretic Deposition (EPD) technique. Different microstructures and electrical behaviours were observed depending on the starting powder. Coatings prepared from commercial powder displayed significant porosity and the superconducting transition width was found to be magnetic-field dependent. Films produced from home-made coprecipitated powder are denser but contain some secondary phases. No dependence of the resistive transition as a function of magnetic field (H ≤ 20 Oe) was observed in that case. [less ▲]

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