Critical state in finite type-II superconducting rings

Navau, Carles; Sanchez, Alvaro; Pardo, Enric; Chen, D.-X.; Bartolomé, Elena; Granados, X.; Puig, T.; Obradors, X.

doi:10.1103/physrevb.71.214507

Cited by 39 publications

(24 citation statements)

References 28 publications

(29 reference statements)

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“…In the latter case, the shape of the field lines is close to that of a bulk cylinder, which at this induction would only be partially penetrated through its outer surface [7,11,26]. For the central region, z/α 2 < 1, and for both systems 1 and 2, the internal magnetic induction is mainly due to the penetration through the thickness of the tube and not through the opening ends.…”

Section: The Spatial Variation Of the Field Attenuationmentioning

confidence: 95%

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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Section: The Spatial Variation Of the Field Attenuationmentioning

confidence: 95%

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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“…The threshold induction Blim at the center of the open tube can be used to estimate the fieldindependent critical current density Jc. If we assume a uniform current density flowing on a macroscopic scale, the threshold induction for a tube of finite length l, thickness d and mean radius ra, can be estimated by [34,35]:…”

Section: Shielding Properties At 77 K In Liquid Nitrogenmentioning

confidence: 99%

Magnetic Shielding Above 1 T at 20 K With Bulk, Large Grain YBCO Tubes Made by Buffer-Aided Top Seeded Melt Growth

Wera

Fagnard

Kumar

et al. 2017

IEEE Trans. Appl. Supercond.

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YBCO tubes of ~ 10 mm diameter closed at one extremity were engineered by a Buffer-Aided Top Seeded Melt Growth fabrication process (BA-TSMG). These tubes can act as efficient "dc" magnetic shields and are observed to reduce axial flux densities of 1.5 T by a factor of 100 at 20 K. Such performances are comparable in magnitude to the record threshold inductions reported for bulk MgB2 and Bi-2212 materials at lower temperatures. Magnetic shielding measurements for open and closed tubes at 77 K also show that the presence of the cap improves substantially the shielding performance at the closed extremity since it reduces the penetration through the open end. This fabrication technique is extremely promising for shielding "dc" stray fields generated by HTS magnets operated in a temperature range obtained by cryocoolers, liquid hydrogen (20 K) or liquid neon (27 K).

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“…ref [29]. B p can also be computed as a function of J c for a ring with finite thickness [30]. Rings and tubes are also recurring shapes in technological applications of superconductors such as permanent magnets [31], superconducting bearings [32] and SQUIDs.…”

Section: Magnetic Flux In Superconductorsmentioning

confidence: 99%

Flux dendrites of opposite polarity in superconductingMgB2rings observed with magneto-optical imaging

et al. 2006

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Critical state in finite type-II superconducting rings

Cited by 39 publications

References 28 publications

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

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

Magnetic Shielding Above 1 T at 20 K With Bulk, Large Grain YBCO Tubes Made by Buffer-Aided Top Seeded Melt Growth

Flux dendrites of opposite polarity in superconductingMgB2rings observed with magneto-optical imaging

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