Improvement of Trapped Magnetic Field of a REBCO Bulk Magnet Activated by Pulsed Field Magnetization in a High-Cooling Power Two-Stage GM-Type Refrigerator

Yokoyama, K.; Oka, Tetsuo

doi:10.1109/tasc.2019.2897481

Cited by 7 publications

(2 citation statements)

References 26 publications

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“…During a PFM process, a spatially inhomogeneous shielding current is generated by the applied field (B a ) due to the inhomogeneous distribution of pinning centers. In other words, magnetic flux tends to penetrate into the sample from 'weak pinning' regions, leading to more intense flux movements in these regions, which affects the final results of trapped field [35,36].…”

Section: Resultsmentioning

confidence: 99%

High performance one-step grown half-moon shaped YBCO bulk superconductors

Wang,

Liu,

Wei

et al. 2024

Supercond. Sci. Technol.

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High-temperature superconducting (HTS) undulator exploiting the high trapped field of HTS bulk superconductors enables the design of extremely short-period insertion devices for synchrotron light sources and free electron lasers. In such a promising application the trapped field performance and the uniformity of the HTS bulk superconductors are essential. In this study, the half-moon shaped YBa2Cu3O7−δ (YBCO) single-grain superconductors have been directly grown by the top-seeded melted-growth (TSMG) method. Half-moon shaped samples directly grown from preforms with four different type of seed crystal arrangements were compared with that cut from larger cylindrical bulk superconductors in regarding to the trapped magnetic fields and correspondingly the distribution. We found that the arrangement of seed crystals greatly affects the melt-growth process and hence the homogeneity of the samples. The one-step grown half-moon shaped samples show higher trapped field (Btrap), 0.542 T for a 24 mm and 0.785 T for a 32 mm diameter sample, and better uniformity of trapped field distribution compared to that obtained from machining with Btrap of 0.427 T and 0.528 T. It was found that the growth sectors would be restricted when the seed crystal was placed at the edge of a preform, and the angle of the seed crystal, parallel or 45° to the long edge would influence the melt growth as well.

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Section: Resultsmentioning

confidence: 99%

High performance one-step grown half-moon shaped YBCO bulk superconductors

Wang,

Liu,

Wei

et al. 2024

Supercond. Sci. Technol.

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“…The modification of the yoke is very easy and inexpensive, and thus, it is advantageous for practical use. In our previous study, the influence of the iron-yoke on the trapped field performance in the high power bulk magnet system was investigated using two-stage GM-type refrigerator with a cooling capacity of 12 W at 20 K [23].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of trapped field of REBCO bulk in a desktop-type magnet system

Yokoyama

Oka

2019

Eng. Res. Express

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We developed a desktop-type bulk magnet system using a Stirling refrigerator and used it to study how to improve the trapped field by pulsed field magnetization (PFM). Although PFM has the advantage that the bulk is activated in a few seconds using an ordinary inexpensive equipment, the amplitude of a trapped field is low as compared with the maximum performance of the material. This paper aims to improve the trapped field by changing the size of soft-iron yoke, which are generally used to extend the pulse width. When a f60-mm GdBCO bulk was magnetized using f64-mm and f80-mm yokes, the maximum flux density and total magnetic flux of large yoke were 13% and 23% higher than those of small one, respectively. Moreover, improvement of trapped field by multi PFM was investigated. When a magnetic field of 5.8 T was applied twice, the maximum trapped field of 1.46 T and the total magnetic flux of 1.86 mWb were achieved.

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