Attempt to Generate a Strong and Uniform Magnetic Field by Face-to-face HTS Bulk Elements in a Magnet System

Oka, Tetsuo; Hirayama, Eri; Takahashi, Yasuhiro; Kanai, Tomoyuki; Ogawa, J.; Fukui, Satoshi; Satô, Takao; Yokoyama, K.; Nakamura, Takashi

doi:10.1016/j.phpro.2015.06.187

Cited by 6 publications

(3 citation statements)

References 8 publications

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“…We employed single-pole or face-to-face pole bulk magnet systems, which are kept at around 30 K by a GM cryocooler in a series of experiments. The actual instances of the system configuration are shown elsewhere [7,8,10]. Figures 2(a) and (b) show how to create a uniform magnetic field by arranging the original convex-and concave-shaped distributions by attaching a 100 mm-wide iron plate (SS400 in Japanese Industrial Standards).…”

Section: Experimental Procedures 21 Magnetic-pole Structures and Arrmentioning

confidence: 99%

“…As the world's first NMR signal has been detected in a field with a uniformity of 1,500 ppm [5], field uniformity less than 1,500 ppm should be necessary to detect the NMR signals. The authors have attempted to obtain flat magnetic field distribution areas by attaching a ferromagnetic iron plate to one of the pole surfaces [7,8]. The magnetic field distribution emitted through the iron plate changed from convex to concave through the shielding effect, and the strayed field became inferior to the original field distribution.…”

Section: Introductionmentioning

confidence: 99%

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Formation of uniform magnetic flux distribution for NMR magnets using HTS bulk magnets activated by pulsed-field magnetization

Oka

Inoue

Tsunoda

et al. 2020

Mater. Res. Express

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Nuclear magnetic resonance (NMR) magnets generally need an extremely uniform magnetic field in the space where the specimens will be placed. Although high temperature superconducting bulk magnets can obtain an intense magnetic field of more than 3 T, the field distribution is intrinsically characterized to be inhomogeneous, showing steep gradient. Aiming at the practical application of compact and portable NMR magnets, the authors have developed magnet systems capable of generating uniform magnetic fields in a narrow space between face-to-face settled magnetic poles, targeting to obtain a uniform magnetic field between the poles. Here, the authors modified the shape of magnetic field distribution from convex to concave by attaching a ferromagnetic iron plate on one of the pole surfaces, and then settled them face to face with a gap of 70 mm. The uniformity of the magnetic field in the x-y plane was experimentally measured and estimated along various z-axis directions. The best uniformity of 463 ppm at 1.25 T was obtained in the experimental evaluation in the x-y plane of 4×4 mm 2 at z=0.5 mm from the iron plate surface. The value of uniformity along the z-direction range was extended from 0.8 mm to a depth of 1.1 mm. These results show that the possible space of NMR signal detection or the available sample size can be enlarged.

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Section: Experimental Procedures 21 Magnetic-pole Structures and Arrmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Formation of uniform magnetic flux distribution for NMR magnets using HTS bulk magnets activated by pulsed-field magnetization

Oka

Inoue

Tsunoda

et al. 2020

Mater. Res. Express

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show abstract

“…To date, most bulk superconductor research has focussed on (RE)-Ba-Cu-O [(RE)BCO] cuprates due to the potential of trapped fields up to 17.6 T [6][7][8]. However, (RE)BCO bulks are difficult to manufacture, brittle and relatively dense (6.4 g cm −3 ) [9,10].…”

Section: Introductionmentioning

confidence: 99%

A new MgB₂ bulk ring fabrication technique for use in magnetic shielding or bench-top NMR systems

Moseley

Wilkinson

Mousavi

et al. 2022

Supercond. Sci. Technol.

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We report a new methodology in bulk MgB2 ring production for use in small-scale magnetic shielding or bench-top NMR systems. This process is a modified field-assisted sintering technique (mFAST) which enables direct formation of the rings without the need for machining or additives into the precursor powder. The shielding and trapped field capabilities of three mFAST MgB2 rings were determined using zero-field- (ZFC) and field-cooled (FC) magnetic experiments. Individual bulks trap magnetic fields up to 1.24T at 20K comparable to the highest published data for a ring sample. It is anticipated that for many applications, multiple rings will be stacked to form the required experimental structure. We find for the three ring stack a trapped field of 2.04T and a maximum shielded field of 1.74T at 20K. The major factor limiting performance at low temperatures are flux jumps which cause rapid loss of the trapped field or shielding capability. Preliminary studies of magnetic field ramp rate dependence on flux jumps were conducted illustrating that even at very slow ramp rates (0.007 T/min) they remain a significant issue. Despite this concern, we conclude that mFAST represents an exciting new fabrication methodology for bulk MgB2 rings.

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Generation of Uniform Magnetic Field between Face-to-Face HTS Bulk Magnets

Oka¹,

Higa

Tsunoda

et al. 2019

J. Phys.: Conf. Ser.

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Aiming to develop the compact nuclear magnetic resonance devices, the authors have been developing the uniform magnetic fields in the space between the face-to-face magnetic poles which contain HTS bulk magnets. The authors deformed the original convex shape of the magnetic field distribution to concave by attaching a ferromagnetic iron plate of 20 mm and 100 mm in diameter on one of the pole surfaces. The magnetic field distribution precisely measured along x-axis changed from concave to convex with increasing distance from the magnetic pole surface, which suggested the presence of magnetically flat region. From the results of mapping on the field uniformity data, we have succeeded in obtaining the field uniformity under 500ppm in the space of 4 x 4 x 0.8 mm3 when the magnetic poles emitting concave and convex field distributions were settled face-to-face with various gaps 30-70 mm. This performance exceeded the target value of 1,500ppm which is necessary to detect the NMR signals.

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Attempt to Generate a Strong and Uniform Magnetic Field by Face-to-face HTS Bulk Elements in a Magnet System

Cited by 6 publications

References 8 publications

Formation of uniform magnetic flux distribution for NMR magnets using HTS bulk magnets activated by pulsed-field magnetization

Formation of uniform magnetic flux distribution for NMR magnets using HTS bulk magnets activated by pulsed-field magnetization

A new MgB₂ bulk ring fabrication technique for use in magnetic shielding or bench-top NMR systems

Generation of Uniform Magnetic Field between Face-to-Face HTS Bulk Magnets

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Attempt to Generate a Strong and Uniform Magnetic Field by Face-to-face HTS Bulk Elements in a Magnet System

Cited by 6 publications

References 8 publications

Formation of uniform magnetic flux distribution for NMR magnets using HTS bulk magnets activated by pulsed-field magnetization

Formation of uniform magnetic flux distribution for NMR magnets using HTS bulk magnets activated by pulsed-field magnetization

A new MgB2 bulk ring fabrication technique for use in magnetic shielding or bench-top NMR systems

Generation of Uniform Magnetic Field between Face-to-Face HTS Bulk Magnets

Contact Info

Product

Resources

About

A new MgB₂ bulk ring fabrication technique for use in magnetic shielding or bench-top NMR systems