Flux trapping in a ring-shaped YBCO bulk by pulsed field magnetization

Fabbri, Massimo; Albano, Pier Giuseppe; Pretelli, M.; Negrini, Francesco; Ohsaki, Hiroyuki

doi:10.1109/77.979850

Cited by 7 publications

(8 citation statements)

References 10 publications

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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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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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show abstract

“…We observed that in our polycrystalline samples it was not as much different as in single crystals. 5 We defined the maximum-to-average ratio as the "inhomogenity" of the flux distribution (Fig. 3b).…”

Section: Field Mappingmentioning

confidence: 99%

“…It is known that the trapped flux is smaller in the case of ZFC magnetization of a given HTS bulk than in the FC mode. 5 Despite of smaller trapped flux, pulse magnetization is more advantageous from certain point of view of practical applications: building and operating the pulse magnetization equipment is economic, moreover "in situ" magnetization of the HTS bulks is also possible, which cannot be realized by FC mode. 1 The practical realization of the pulse field magnetization of HTS bulks is similar to the magnetizing process of conventional permanent magnets (PM), where the subjected material is ferrite, Alnico alloy, rare-earth magnet, etc.…”

Section: Introductionmentioning

confidence: 99%

YBCO bulks for preparation of permanent magnets

Szalay

Bertalan

Vajda

et al. 2005

Journal of the European Ceramic Society

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“…As a result, it has been very challenging to magnetize bulk superconducting rings with high trapped fields. In the literature to date, reported trapped fields in bulk superconducting rings magnetized by PFM have been less than 0.35 T at the centre of a single bulk superconducting ring [13]- [16].…”

Section: Introductionmentioning

confidence: 97%

“…The heating problem is worse in the case of bulk superconducting rings during PFM because the magnetic flux penetrates from both the inner and outer edges of the sample [9], [10]. This can result in significant heating [11], causing the magnetization current to be disrupted and the trapped field to reduce significantly [12], [13]. As a result, it has been very challenging to magnetize bulk superconducting rings with high trapped fields.…”

Section: Introductionmentioning

confidence: 99%

Trapped Fields >1 T in a Bulk Superconducting Ring by Pulsed Field Magnetization

Tsui¹,

Moseley

Dennis³

et al. 2022

IEEE Trans. Appl. Supercond.

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One potential application of magnetized RE-Ba-Cu-O (where RE = rare earth or Y) bulk superconductors is as a highfield alternative to conventional permanent magnets in desktop NMR and MRI systems. Pulsed field magnetization (PFM) is one of the most promising practical methods of magnetizing such bulks. However, the trapped fields obtained by PFM are much lower than those obtained using quasi-static methods like field-cooling magnetization (FCM) due to heating during PFM. Furthermore, bulk superconducting rings have proved more difficult to magnetize via PFM than discs. The reported trapped fields in single bulk superconducting rings magnetized by PFM are less than 0.35 T at the centre of the bore due to thermomagnetic instabilities. In this work, systematic PFM measurements on a bulk Gd-Ba-Cu-O ring were carried out and a trapped field of 1.3 T at 55 K was achieved using a multi-pulse, stepwise cooling (MPSC) method. In the MPSC method, a sequence of pulsed fields is used to magnetize the ring bulk. The pulsed field is increased in small increments and the sample temperature is decreased sequentially. Consequently, as some field is already trapped after the first pulse, the motion of the flux for subsequent pulses will be reduced, leading to less heat generated in the bulk sample. This greatly improves the thermomagnetic stability of the PFM process, enabling larger trapped fields.

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Flux trapping in a ring-shaped YBCO bulk by pulsed field magnetization

Cited by 7 publications

References 10 publications

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

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

YBCO bulks for preparation of permanent magnets

Trapped Fields >1 T in a Bulk Superconducting Ring by Pulsed Field Magnetization

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