Magnetic shielding and trapping properties of BPSCCO superconducting tubes

Plecháček, V.; Sedmidubský, David; Knı́žek, K.; Pollert, E.; Janú, Z.; Tichý, R.

doi:10.1109/77.402604

Cited by 13 publications

(10 citation statements)

References 7 publications

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“…The same results were established for superconducting disks made from YBCO powder and subjected to perpendicular fields [20,21]. Yet other studies on bulk BSCCO tubes [3,22] measured a field attenuation that decreases with frequency, whereas the attenuation was shown to slowly increase with frequency for a YBCO superconducting tube [23].…”

Section: Introductionsupporting

confidence: 72%

Spectra of quantum systems in superstrong inertial force fields

Денисов¹,

Kravtsov²

2002

Quantum Electron.

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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 J c (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.

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Section: Introductionsupporting

confidence: 72%

Spectra of quantum systems in superstrong inertial force fields

Денисов¹,

Kravtsov²

2002

Quantum Electron.

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“…Early experimental investigations of the magnetic shielding of superconducting tubes were carried by measuring the magnetic field inside a tube (either made of low-T c or high-T c material) subjected to an external magnetic field applied either axially or transversally. [6][7]. Models were then developed to describe the experimental observations.…”

Section: Introductionmentioning

confidence: 99%

Magnetic shielding properties of high-T_csuperconducting hollow cylinders: model combining experimental data for axial and transverse magnetic field configurations

Fagnard

Dirickx

Ausloos

et al. 2009

Supercond. Sci. Technol.

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Magnetic shielding efficiency was measured on high-T c superconducting hollow cylinders subjected to either an axial or a transverse magnetic field in a large range of field sweep rates, dB app /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 µT/s and 10 mT/s for both directions of the applied magnetic field. The experimental curves of the internal field vs. the applied field, B in (B app), show that, at a given sweep rate, the magnetic field for which the penetration occurs, B lim , is lower for the transverse configuration than for the axial configuration. A power law dependence with large exponent, n', is found between B lim and dB app /dt. The values of n' are nearly the same for both configurations. We show that the main features of the curves B in (B app) can be reproduced using a simple 2-D model based on the method of Brandt involving a E(J) power law with an n-exponent and a field-dependent critical current density, J c (B), (following the Kim model: J c = J c0 (1+B/B 1)-1). In particular, a linear relationship between the measured n'-exponents and the nexponent 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.

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“…Hence, as in most previous works on the fabrication of large superconducting magnetic shields [3,6,10,[12][13][14][15][16][17][18], we focus on polygrain materials [19,20]. We assume that the shielding polycrystalline material satisfies the three following constitutive laws:…”

Section: Constitutive Lawsmentioning

confidence: 99%

Field penetration into hard type-II superconducting tubes: effects of a cap, a non-superconducting joint, and non-uniform superconducting properties

Denis

Dirickx

Vanderbemden

et al. 2007

Supercond. Sci. Technol.

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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.

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Magnetic shielding and trapping properties of BPSCCO superconducting tubes

Cited by 13 publications

References 7 publications

Spectra of quantum systems in superstrong inertial force fields

Spectra of quantum systems in superstrong inertial force fields

Magnetic shielding properties of high-T_csuperconducting hollow cylinders: model combining experimental data for axial and transverse magnetic field configurations

Field penetration into hard type-II superconducting tubes: effects of a cap, a non-superconducting joint, and non-uniform superconducting properties

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Magnetic shielding and trapping properties of BPSCCO superconducting tubes

Cited by 13 publications

References 7 publications

Spectra of quantum systems in superstrong inertial force fields

Spectra of quantum systems in superstrong inertial force fields

Magnetic shielding properties of high-Tcsuperconducting hollow cylinders: model combining experimental data for axial and transverse magnetic field configurations

Field penetration into hard type-II superconducting tubes: effects of a cap, a non-superconducting joint, and non-uniform superconducting properties

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Product

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Magnetic shielding properties of high-T_csuperconducting hollow cylinders: model combining experimental data for axial and transverse magnetic field configurations