A record-high trapped field of 1.61 T in MgB<sub>2</sub> bulk comprised of copper plates and soft iron yoke cylinder using pulsed-field magnetization

Hirano, Tatsuya; Takahashi, Yuhei; Namba, Sora; Naito, Tomoyuki; Fujishiro, Hiroyuki

doi:10.1088/1361-6668/ab9542

Cited by 13 publications

(40 citation statements)

References 40 publications

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“…We relate this to the negative role played by flux jumps in MgB 2 PFM. Indeed in MgB 2 bulks, the iterative pulsing leads to the flux front uniformly penetrating the sample without flux jumps, as shown in figure 10 [26]. This behaviour is commonly explained by the reduction in heat generated with repeated pulsing [27,26].…”

Section: Factors Influencing Final Trapped Fieldmentioning

confidence: 94%

“…Indeed in MgB 2 bulks, the iterative pulsing leads to the flux front uniformly penetrating the sample without flux jumps, as shown in figure 10 [26]. This behaviour is commonly explained by the reduction in heat generated with repeated pulsing [27,26]. However, the interplay between the remanent magnetisation and penetrating flux is still not well understood.…”

Section: Factors Influencing Final Trapped Fieldmentioning

confidence: 99%

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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: 94%

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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“…As a result, bulk superconducting rings are more susceptible to thermomagnetic instabilities during the PFM process, making it very challenging to magnetize samples of this geometry to high trapped fields. Thus, in the literature to date, reported trapped fields in bulk superconducting rings magnetized by PFM are less than 0.35 T at the centre of a single ring bulk compared to those magnetized by FC [10,11,12,13].…”

Section: Introductionmentioning

confidence: 95%

Waveform Control Pulsed Field Magnetization of RE-Ba-Cu-O Bulk Superconducting Rings

Tsui¹,

Moseley

Dennis³

et al. 2022

IEEE Trans. Appl. Supercond.

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One of the potential applications of ring-shaped, single grain RE-Ba-Cu-O bulk superconductors is in desktop magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) systems as an alternative to conventional permanent magnets. The higher magnetic field available from magnetized bulk superconductors could significantly improve the performance of such systems, as well as reduce their size and increase portability. The pulsed field magnetization (PFM) method provides a fast, compact and cost-effective method for magnetizing these materials as trapped field magnets. However, bulk superconducting rings are very susceptible to thermomagnetic instabilities during the PFM process, and thus, to date, the reported trapped fields in ring bulks magnetized by PFM are less than 0.35 T at the centre of single rings.In this work, we demonstrate that the trapped field in a superconducting ring bulk can be enhanced significantly by optimizing the waveform of the magnetizing pulse used in the PFM method. This optimization can be achieved easily by using an Insulated Gate Bipolar Transistor as a fast-switching device with a controllable switching frequency in the pulse-generating electric circuit. Our findings represent a key step forward in utilizing bulk, singlegrain superconducting rings magnetized by PFM in portable magnet systems.

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“…In 2014, Durrell et al reported a trapped field of 17.6 T at 29 K in a stack of two silver doped GdBCO superconducting bulk samples [46]. A record-high trapped field of 16.1 T in MgB 2 bulk has been recently achieved at 20 K by Hirano et al using pulsed-field magnetization (PFM) [47]. The possibility of the application of bulk superconductors to electrical machines has been discussed by many researchers.…”

Section: Superconducting Materials Applied To Electrical Machinesmentioning

confidence: 99%

Alternating Current Loss of Superconductors Applied to Superconducting Electrical Machines

Zhang¹,

Wen²,

Grilli

et al. 2021

Energies

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Superconductor technology has recently attracted increasing attention in power-generation- and electrical-propulsion-related domains, as it provides a solution to the limited power density seen by the core component, electrical machines. Superconducting machines, characterized by both high power density and high efficiency, can effectively reduce the size and mass compared to conventional machine designs. This opens the way to large-scale purely electrical applications, e.g., all-electrical aircrafts. The alternating current (AC) loss of superconductors caused by time-varying transport currents or magnetic fields (or both) has impaired the efficiency and reliability of superconducting machines, bringing severe challenges to the cryogenic systems, too. Although much research has been conducted in terms of the qualitative and quantitative analysis of AC loss and its reduction methods, AC loss remains a crucial problem for the design of highly efficient superconducting machines, especially for those operating at high speeds for future aviation. Given that a critical review on the research advancement regarding the AC loss of superconductors has not been reported during the last dozen years, especially combined with electrical machines, this paper aims to clarify its research status and provide a useful reference for researchers working on superconducting machines. The adopted superconducting materials, analytical formulae, modelling methods, measurement approaches, as well as reduction techniques for AC loss of low-temperature superconductors (LTSs) and high-temperature superconductors (HTSs) in both low- and high-frequency fields have been systematically analyzed and summarized. Based on the authors’ previous research on the AC loss characteristics of HTS coated conductors (CCs), stacks, and coils at high frequencies, the challenges for the existing AC loss quantification methods have been elucidated, and multiple suggestions with respect to the AC loss reduction in superconducting machines have been put forward. This article systematically reviews the qualitative and quantitative analysis methods of AC loss as well as its reduction techniques in superconductors applied to electrical machines for the first time. It is believed to help deepen the understanding of AC loss and deliver a helpful guideline for the future development of superconducting machines and applied superconductivity.

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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

Cited by 13 publications

References 40 publications

Improved pulsed field magnetisation in MgB₂ trapped-field magnets

Improved pulsed field magnetisation in MgB₂ trapped-field magnets

Waveform Control Pulsed Field Magnetization of RE-Ba-Cu-O Bulk Superconducting Rings

Alternating Current Loss of Superconductors Applied to Superconducting Electrical Machines

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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

Cited by 13 publications

References 40 publications

Improved pulsed field magnetisation in MgB2 trapped-field magnets

Improved pulsed field magnetisation in MgB2 trapped-field magnets

Waveform Control Pulsed Field Magnetization of RE-Ba-Cu-O Bulk Superconducting Rings

Alternating Current Loss of Superconductors Applied to Superconducting Electrical Machines

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Product

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About

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

Improved pulsed field magnetisation in MgB₂ trapped-field magnets

Improved pulsed field magnetisation in MgB₂ trapped-field magnets