Magnetic shielding of MgB<sub>2</sub> tubes in applied DC and AC field

Cavallin, T.; Quarantiello, R.; Matrone, A.; Giunchi, G.

doi:10.1088/1742-6596/43/1/248

Cited by 26 publications

(19 citation statements)

References 3 publications

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“…The traditional solution of this problem consists in using a piece of ferromagnetic material instead, which can divert the magnetic flux outside the region to be protected [1]. However, hard type-II superconductors, which are strongly diamagnetic, can shield a magnetic field more efficiently than ferromagnetic materials do [2][3][4][5][6], In a recent work [7], we have studied numerically and experimentally the shielding properties of open type-II superconducting tubes that were subjected to a source field applied parallel to the tube axis (parallel geometry). Three factors were considered to evaluate the quality of the shields: (i) the maximum induction that can be strongly attenuated, called B lim , (ii) the spatial variation of the field attenuation, and (iii), the frequency dependence of the field attenuation.…”

Section: Introductionmentioning

confidence: 99%

“…The type of material that can be used, and hence the quality of its superconducting properties and the typical dimensions that can be obtained for a shield, depend on the operating temperature of the shield. If temperatures lower than 40 K are allowed by the application, magnesium diboride (MgB 2 ) can be used to make efficient magnetic shields [6]. The reactive liquid infiltration method allows one to realize superconducting tubes with lengths of several tens of centimetres [8,9].…”

Section: Introductionmentioning

confidence: 99%

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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: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

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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“…In cryogenic applications, shielding with superconducting materials is found to be more effective than conventional ferromagnets and can be implemented easily since the cooling system is directly available. In particular, high temperature superconductors (HTS) hollow cylinders, made of Bi 2 Sr 2 Ca 2 Cu 3 O 10 (Bi-2223) [9,10], Bi 2 Sr 2 CaCu 2 O 8 (Bi-2212) [11,12], YBa 2 Cu 3 O 7 (YBCO) [13,14] or MgB 2 [15,16], have already demonstrated their shielding abilities. Hybrid ferromagnetic/superconductor structures can also be used as DC magnetic shields [17,18].…”

Section: Introductionmentioning

confidence: 99%

A comparative study of triaxial and uniaxial magnetic shields made out of YBCO coated conductors

Wera

Fagnard

Levin

et al. 2015

Supercond. Sci. Technol.

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Persistent current loops of arbitrary size can be made from currently manufactured RE123 coated conductors. Our previous work has shown that an assembly of such loops is able to shield effectively quasi static axial magnetic field due to the absence of resistive joint. The shielding effectiveness depends on the aspect ratio and the number of layers. In the present work we study experimentally the detailed magnetic response of two different configurations of the magnetic shields for various orientations of the applied field. Using a 3-axis Hall probe we determine the amplitude of magnetic field generated by the induced persistent currents and its direction with respect to the applied field. The effectiveness of the uniaxial shield decreases strongly when the applied field is not collinear with its axis. In the triaxial (Polywell type) structure comprised of three pairs of coils whose axes are mutually orthogonal, the field attenuation is shown to be only weakly dependent on the direction of the magnetic field. We discuss the properties of the triaxial shield and the ways to improve its screening performance.

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“…The process, based on Reactive Mg Liquid Infiltration (Mg-RLI) of boron powders [5], is simple and avoids the use of Hot Pressing apparatus, a technique that limits the size of the manufacts. Up to now, several MgB 2 small prototypes have been manufactured with the Mg-RLI process and their superconducting characteristics in the magnetic shielding have been characterized [6]. The shapes of these prototype are: tubes, rings, plates, cylinders, discs and their dimension, as lab prototypes, was of the order of tens of cm [7].…”

Section: Introductionmentioning

confidence: 99%

MGB[sub 2] CYLINDRICAL CUP FOR MAGNETIC SHIELDING IN PULSE TUBE CRYOSTAT

Giunchi¹,

Bassani²,

Hassel³

et al. 2010

AIP Conference Proceedings

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We present the design and measurements on a magnetic shield based on MgB 2 integrated in a commercial pulse tube cryostat. The shield is fabricated by an innovative manufacturing process, useful to obtain bulk MgB 2 superconductor of high density. The shield is ideal for shielding at cryogenic temperatures lower than 35K. With respect to the conventional cryogenic superconducting shields, made e.g. by lead foil, the actual MgB 2 shield presents the advantages of a very high temperature margin and a lower density (2.4 g/cm 3 ). The last characteristic will be particularly useful in space applications. Furthermore, with a superconducting transition temperature of about 39K, it is possible to reduce markedly the Earth field trapped during the cool down of thin film based devices fabricated from materials with lower transition temperatures. The shape and the dimensions can be varied according to the needs. The prototype shield has a sample volume with the diameter of 37 mm and the height of 35 mm. As a test for the functionality of the shield we have measured properties of a SQUID magnetic field sensor showing significant reduction of ambient magnetic noise and interference. The shielding capability of the present MgB 2 cup are reviewed and the possible applications of these line of products will be discussed.

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Magnetic shielding of MgB₂ tubes in applied DC and AC field

Cited by 26 publications

References 3 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

A comparative study of triaxial and uniaxial magnetic shields made out of YBCO coated conductors

MGB[sub 2] CYLINDRICAL CUP FOR MAGNETIC SHIELDING IN PULSE TUBE CRYOSTAT

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Magnetic shielding of MgB2 tubes in applied DC and AC field

Cited by 26 publications

References 3 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

A comparative study of triaxial and uniaxial magnetic shields made out of YBCO coated conductors

MGB[sub 2] CYLINDRICAL CUP FOR MAGNETIC SHIELDING IN PULSE TUBE CRYOSTAT

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Magnetic shielding of MgB₂ tubes in applied DC and AC field