Pulse-Field Magnetization for Disc-Shaped MgB<sub>2</sub>Bulk Magnets

Miyazaki, Taisuke; Fukui, Satoshi; Ogawa, J.; Satô, Takao; Oka, Tetsuo; Scheiter, J.; Hasler, Wolfgang; Kulawansha, Eranda; Yuanding, Zhao; Yokoyama, K.

doi:10.1109/tasc.2016.2639298

Cited by 11 publications

(5 citation statements)

References 11 publications

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“…In the existing literature, studies optimising the final trapped field in MgB 2 bulk samples have focussed on exploring bulk properties [22,23] or the use of split-coil magnetic field geometries [24]. The effect of interfacial cooling has not been explicitly explored despite numerical studies indicating its significance during magnetisation experiments [25].…”

Section: Factors Influencing Final Trapped Fieldmentioning

confidence: 99%

Improved pulsed field magnetisation in MgB₂ trapped-field magnets

Moseley

Matthews

Zhou

et al. 2021

Supercond. Sci. Technol.

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Bulk superconductors can act as trapped-field magnets with the potential to be used for many applications such as portable medical magnet systems and rotating machines. Maximising the trapped field, particularly for practical magnetisation techniques such as pulsed field magnetisation (PFM), still remains a challenge. PFM is a dynamic process in which the magnetic field is driven into a superconducting bulk over milliseconds. This flux motion causes heating and a complex interplay between the magnetic and thermal properties. In this work, the local flux density during PFM in a MgB 2 bulk superconductor has been studied. We find that improving the cooling architecture increases the flux trapping capabilities and alters the flux motion during PFM. These improvements lead to the largest trapped field (0.95T) for a single MgB 2 bulk sample magnetised by a solenoidal pulsed field magnet. The findings illustrate the fundamental role bulk cooling plays during PFM.

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Section: Factors Influencing Final Trapped Fieldmentioning

confidence: 99%

Improved pulsed field magnetisation in MgB₂ trapped-field magnets

Moseley

Matthews

Zhou

et al. 2021

Supercond. Sci. Technol.

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“…We have achieved the trapped field of B T (PFM) = 5.20 T on a GdBaCuO bulk 45 mm in diameter at 29 K using a modified multi-pulse technique with stepwise cooling (MMPSC) [17], which is a record-high B T (PFM) for REBaCuO bulk by PFM to date. The PFM technique has also been applied to MgB 2 bulks [27][28][29][30][31][32]. B T (PFM) = 0.81 T was achieved at 14 K for a high-J c MgB 2 bulk fabricated by the hot isostatic pressing (HIP) method magnetized using a copper solenoid coil, in which B T (FCM) = 2.23 T was trapped at 16 K by FCM [29].…”

Section: Introductionmentioning

confidence: 99%

“…The PFM technique has also been applied to MgB 2 bulks [27][28][29][30][31][32]. B T (PFM) = 0.81 T was achieved at 14 K for a high-J c MgB 2 bulk fabricated by the hot isostatic pressing (HIP) method magnetized using a copper solenoid coil, in which B T (FCM) = 2.23 T was trapped at 16 K by FCM [29]. However, flux jumps took place frequently during PFM in the high-J c MgB 2 bulks and consequently the final B T (PFM) value decreased for larger pulsed fields.…”

Section: Introductionmentioning

confidence: 99%

A record-high trapped field of 1.61 T in MgB₂ bulk comprised of copper plates and soft iron yoke cylinder using pulsed-field magnetization

Hirano

Takahashi

Namba

et al. 2020

Supercond. Sci. Technol.

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A trapped field of B T = 1.61 T was experimentally achieved at the central surface of an MgB 2 bulk composite (60 mm in diameter and 20 mm in height) at 20 K by double pulsed-field magnetization (PFM) using a split-type coil. The composite bulks consisted of two MgB 2 ring bulks sandwiched by thin copper ring plates, which were then stacked, and a soft iron yoke cylinder was inserted in the central bore of the rings. The copper ring plates delayed the rise time and duration of the magnetic pulse due to eddy currents. The inserted soft iron yoke attracted the magnetic flux and enhanced the trapped field strength mainly due to its large permeability. As a result, the trapped field was enhanced from B T = 0.34 T for the single MgB 2 ring bulk without the copper plates and soft iron yoke to B T = 1.00 T for the composite with both copper plates and the soft iron yoke. The inserted soft iron yoke can be exploited to enhance the trapped field because the intrinsic B T of the single MgB 2 ring bulk was smaller than the saturation field of the yoke (∼2 T). Using an optimized second pulse application after suitable flux trapping from the first pulse application, the trapped field was enhanced considerably to B T (2nd) = 1.61 T, which is a record-high trapped field for an MgB 2 bulk by PFM to date. The combination of the longer magnetic pulse application by the copper plates, the enhancement of the effective applied field by the inserted soft iron yoke, and the double pulse application using split-type coil is an effective technique to enhance the trapped field in the MgB 2 bulk using PFM.

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“…All this leads to the conclusion that there is a change of the current flow radius at elevated temperatures, being due to a gradual decoupling of the MgB 2 grains. This observation has, therefore, important consequences for the development of MgB 2 -based superconducting permanent magnets [35][36][37][38] with higher trapped fields.…”

Section: Resultsmentioning

confidence: 99%

Pinning Force Scaling Analysis of Polycrystalline MgB2

Koblischka

Wiederhold

Koblischka-Veneva

et al. 2020

J Supercond Nov Magn

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Flux pinning force scaling $f=F_{p}/F_{p,\max \limits }$ f = F p / F p , max vs. h = Ha/Hirr was performed on a variety of pure MgB2 samples, including a spark plasma sintered (SPS) one and a series of samples sintered at various reaction temperatures ranging between 775 and 950 ∘C. The SPS sample exhibits a well-developed scaling at all temperatures, and also the sintered samples prepared at 950 ∘C; however, the obtained peak positions of the pinning force scalings are distinctly different: The SPS sample reveals dominating pinning at grain boundaries, whereas the dominating pinning for the other one is point-pinning. All other samples studied reveal an apparent non-scaling of the pinning forces. The obtained pinning parameters are discussed in the framework of the Dew–Hughes’ pinning force scaling approach.

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Pulse-Field Magnetization for Disc-Shaped MgB₂Bulk Magnets

Cited by 11 publications

References 11 publications

Improved pulsed field magnetisation in MgB₂ trapped-field magnets

Improved pulsed field magnetisation in MgB₂ trapped-field magnets

A record-high trapped field of 1.61 T in MgB₂ bulk comprised of copper plates and soft iron yoke cylinder using pulsed-field magnetization

Pinning Force Scaling Analysis of Polycrystalline MgB2

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Pulse-Field Magnetization for Disc-Shaped MgB2Bulk Magnets

Cited by 11 publications

References 11 publications

Improved pulsed field magnetisation in MgB2 trapped-field magnets

Improved pulsed field magnetisation in MgB2 trapped-field magnets

A record-high trapped field of 1.61 T in MgB2 bulk comprised of copper plates and soft iron yoke cylinder using pulsed-field magnetization

Pinning Force Scaling Analysis of Polycrystalline MgB2

Contact Info

Product

Resources

About

Pulse-Field Magnetization for Disc-Shaped MgB₂Bulk Magnets

Improved pulsed field magnetisation in MgB₂ trapped-field magnets

Improved pulsed field magnetisation in MgB₂ trapped-field magnets

A record-high trapped field of 1.61 T in MgB₂ bulk comprised of copper plates and soft iron yoke cylinder using pulsed-field magnetization