10T Class Trapped Field Properties of a Large Gd-Ba-Cu-O Bulk Superconductor

J J n c c where E c (=10 −4 V m −1 ) is the reference electric field and J c (=4.8 × 10 8 A m −2 ) is the critical current density under zero field, which is a typical J c value at T s = 50 K for the REBaCuO bulk [7]. J c is assumed to be independent of applied magnetic field [7]. For an 'infinite disk bulk' with the same O.D., not the 'infinite ring bulk', the fully magnetized trapped field is estimated to be B z * = μ 0 J c R = 19.30 T (R: radius of the disk bulk) by 2 Supercond. Sci. Technol. 30 (2017) 085008 H Fujishiro et al

Section: Numerical Simulation Frameworkmentioning

confidence: 99%

Simulation studies of mechanical stresses in REBaCuO superconducting ring bulks with infinite and finite height reinforced by metal ring during field-cooled magnetization

Fujishiro

Ainslie

Takahashi

et al. 2017

“…For practical engineering applications of HTS bulks, more detailed data on a large bulk in a wide temperature range will be necessary. The measurements of trapped magnetic fields at 40-75 K were carried out by magnetizing the 46 mm-sized Gd-QMG bulk using a 10 T superconducting magnet [29,30]. The bulk was cooled with a refrigerator in the presence of external fields of 6, 8.5 and 10 T. After the removal of the external field, the trapped field was recorded using a Hall sensor that was directly glued onto the surface of the bulk.…”

Section: Progress In Gd-qmg Bulk Melt-processed In Airmentioning

confidence: 99%

Performance and applications of quench melt-growth bulk magnets

Nariki¹,

Teshima²,

Morita³

2016

This paper describes the progress in quench melt-growth (QMG) bulk magnets, developed by the Nippon Steel & Sumitomo Metal Corporation, which consist of single crystalline RE123 phase and finely dispersed RE211 particles. QMG bulks can trap high magnetic fields. The field-trapping ability of QMG bulks is largely increased with an improvement in its Jc and size, promising the realization of various applications such as flywheel energy-storage systems, ship motors, NMR/MRI spectrometers, wind-power generators and so on. Intensive research has revealed that the optimal RE element is different depending on application requirements. Gd-QMG bulk is the most promising material for several high-field engineering applications. The trapped magnetic field of Gd-QMG bulk 60 mm in diameter at 77 K is twice as large as that of Y-QMG bulk with a similar size due to its excellent Jc properties. The large Gd-based QMG bulks up to 150 mm in diameter are fabricated by incorporating the RE compositional gradient method. Compact NMR/MRI spectrometers are one of the promising applications of bulk superconductors. Eu-QMG bulks are suitable for NMR magnets. NMR applications require extremely homogeneous magnetic fields. In the Eu-system, the small paramagnetic moment of a Eu ion compared to a Gd ion improves the field homogeneity in the bulk. For the application of current leads, Dy-based QMG is available by utilizing a low thermal conductivity.

“…The higher B T FCM can be realised at lower temperatures because of the increase in J c . Therefore, a 10T class bulk magnet can be realised around 40K using bulks 45-60mm in diameter and 15mm in thickness reinforced by a stainless steel ring [8]. Further high B T FCM over 17T was obtained for the specially reinforced YBCO [9] and GdBCO [10] bulks below 30K.…”

Section: Introductionmentioning

confidence: 98%

Trapped magnetic-field properties of prototype for Gd-Ba-Cu-O/MgB₂hybrid-type superconducting bulk magnet

Naito

Mochizuki

Fujishiro

et al. 2016

We have studied experimentally and numerically the trapped magnetic-field properties of a hybrid-type superconducting bulk magnet, which comprised an inner Gd-Ba-Cu-O (GdBCO) disk-bulk and an outer MgB2 ring-bulk, under field-cooled magnetization (FCM) and pulsed-field magnetization (PFM). The trapped field by FCM at the center of the hybrid bulk was 4.5 T at 20 K, which was 0.2 T higher than that of the inner GdBCO disk-bulk without MgB2 ring-bulk. The experimental results by FCM were quantitatively reproduced by the numerical estimations for a model, which makes it possible to understand the trapped field properties of the hybrid bulk. The total magnetic flux by FCM, which was estimated numerically, was enhanced by about 1.7 times from 0.91 mWb of the single GdBCO bulk to 1.53 mWb of the hybrid bulk. We also succeeded in magnetizing the whole hybrid bulk by applying multi-pulsed-fields. The central trapped field of 1.88 T was not enhanced, but the total magnetic flux, which was obtained experimentally, was evidently increased by 2.5 times (0.25 0.62 mWb) for the hybrid bulk. The obtained results suggest that the hybridization is effective to enhance the total magnetic flux. To confirm the reinforcing effect of the MgB2 ring to the GdBCO disk during the cooling and magnetization processes, we have measured the thermal dilatation, , of the GdBCO, MgB2 and stainless steel. As a result, the thermal dilatation of MgB2 was smaller than that of GdBCO. MgB2 ring-bulk shows no compression effect to resist the hoop stress of the GdBCO disk-bulk during the FCM process. The reinforcing material such as the stainless steel ring must be set outside the GdBCO disk-bulk.