The improvement in magnetic shielding by use of a double-cylinder configuration of high-Tcoxide superconductors

Itoh, M.; Ohyama, Takashi; Minemoto, Takumi; Numata, Koichi; Hoshino, Kazutomo

doi:10.1088/0022-3727/25/11/010

Cited by 28 publications

(8 citation statements)

References 10 publications

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“…The effect of Bex on the inner magnetic flux density (Bi,,) within the single-and double-superimposed cylinders, the distribution of the maximum shielded magnetic flux density (B5) within the cylinders, and the values of Bs as a function of the length of the outer magnetic cylinder, were measured with the use of a GaAs Hall device as reported in Refs . (2) and (4). The sensitivity of the measuring system was 100 mV/gauss.…”

Section: Methodsmentioning

confidence: 99%

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Magnetic Shielding Effect of High-Tc Superconduction Cylinder Using the Ferromagnetic Cylinder

et al. 1995

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Non-member Takumi Minemoto (Kobe University)As one of the basic research areas for the improvement of magnetic shielding effects and the fabrication of largesized cylinders, the present paper shows how the shielding is improved by superimposing a single-or doublemagnetic cylinder such as a soft iron cylinder over a high-critical-temperature (high-T,) superconducting cylinder such as a Y-Ba-Cu-O (YBCO) cylinder. The value of the maximum shielded magnetic field (B5) for the superimposed cylinder by using a double-magnetic cylinder was found about 50 times greater than that of a superconducting YBCO cylinder. The values of B, are systematically measured by changing the lengths of single-and double-soft-iron cylinders at a temperature of 77.4 K, and are analyzed by using several different models, with an important criterion being derived for designing an effective shield of the vessel. In addition, it was found that the experimental values of B, agree well with theoretical values.

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Section: Methodsmentioning

confidence: 99%

“…(4) and (10). The outside of YBCO cylinder (2.5 rnm inner radius, 2 mm thickness, 19 mm length) was wrapped with several turns of fluoroplastic (PTFE) tape, making use of the troidal winding method, in order to avoid sudden temperature changes.…”

Section: Methodsmentioning

confidence: 99%

Magnetic Shielding Effect of High-Tc Superconduction Cylinder Using the Ferromagnetic Cylinder

et al. 1995

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“…The BPSCCO powder (grain size: about 10 mm or smaller) was fabricated as described in Ref. [2], and fed into a rubber tube which pressed the powder into the shape of cylinder. The BPSCCO cylinder was fabricated under a pressure of 1.3 ton/cm 2 by use of the cold isostatic press (CIP) method, and then sintered in laboratory air at temperatures ranging from 830 to 845 8C, over times ranging from 24 to 96 h. Fig.…”

Section: Methodsmentioning

confidence: 99%

Analysis of the magnetic distribution within a high-temperature superconductor magnetic shielding cylinder by use of the finite element method

Omura

Kotani

Yasu

et al. 2006

Journal of Physics and Chemistry of Solids

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“…[5] and [6]. The sensitivity of the measuring system was 100 mvilgauss at a temperature of 77.4 K. Figure 1 shows a schematic diagram of the experimental arrangement used to measure the magnetic NPS at the center of the BPSCCO cylinder under conditions of the boiling point of liquid nitrogen (77.4 K).…”

Section: Experimental Procedure!mentioning

confidence: 99%

Measurements of the magnetic noise spectra in HTS cylinders for magnetic shielding

Itoh

Iguchi

Minemoto

et al. 1997

IEEE Trans. Appl. Supercond.

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Idealized magnetic shielded vessels can be realized by use of high-critical temperature superconductors (HTS). It is, however, generally, very difticult to evaluate the limit of the value of magnetic shielding and the fluctnation o f the magnetic flux within the HTS vessel.In this present research, the magnetic noise power spectra (NPS) within the Bi-Pb-Sr-Ca-Cu-0 (BPSCCO) cylinder was measured using a HTS dc-SQUID, under an application of a magnetic field Beu less than the value o f Bs (the maximum shielded magnetic flux density, 3.2x10-4 T at 77.4 K). The value of NPS was determined as 50x10-6 OOz/Hz at 1 kHz excluding Bex which was the background noise o f the SQUID control system, and 1.0~10-5 #uZ/Hz at 1 kHz for a B~x of 3.0x10-4 T. The value of NPS at 1 kHz increased linearly with values of Bex in the region of 0.0 T to 3.0 x10-4 T.Also shown are the important criteria for the design of effective shielded vessels for low magnetic measurements. I. bTIRODUCTIONThe idealized magnetic shielded vessel can be realized by use of a high-critical temperature superconductor (HTS). Shielded vessels are required in many applications to reduce the influence of environmental magnetic fields, and to protect the environment from the leakage of strong generated magnetic fields. There are increasing needs for shields capable o€ limiting regions to very low values of the magnetic flux density, less than 10-10 T, such as in biomagnetic measurements. It is difficult, however, to evaluate the behavior of the magnetic field, the fluctuation of the magnetic flux, and the value of the limit of the magnetic shielding under conditions of the maximum shielded magnetic flux density B,.In order to simplify the present theoretical analysis, the evaluation of the magnetic shielding effect is limited to an HTS cylinder, such as a BPSCCO (Bi-Pb-Sr-Ca-Cu-0) cylinder in a homogeneous excited dc magnetic flux density Bex. The magnetic noise power spectra @PS) is measured Manuscript rcceived August 25, 1996 with the use of the HTS dc-SQUID system and spectrum analyzer. Experimental results reveal several characteristics of the magnetic shielding within a superconducting BPSCCO cylinder for evaluating the shielding effects. Among these are the effects of Be, on the magnetic €ield, the magnetic NPS under the influence of B,, (less than the value of Bs), and the relationship between the 1/f fluctuation and the value of B,,, where f is the frequency. As reported in Refs. [l] -[4], the degree of magnetic shielding for a single-BPSCCO can be improved by use of a configuration consisting of the superposition of a soft-iron cylinder over a BPSCCO cylinder; termed the superimposed BPSCCO cylinder. Also discussed are the magnetic shielding effects and magnetic NPS for a superimposed BPSCCO cylinder. EXPERIMENTAL PROCEDURE!Magnetic shielding effects were evaluated for all cylinders placed within an excitation magnetic flux density Be, (homogeneous dc magnetic field), applied parallel to the axial direction of the cylinders. The effect of B,, on the inn...

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The improvement in magnetic shielding by use of a double-cylinder configuration of high-T_coxide superconductors

Cited by 28 publications

References 10 publications

Magnetic Shielding Effect of High-<i>T<sub>c</sub></i> Superconduction Cylinder Using the Ferromagnetic Cylinder

Magnetic Shielding Effect of High-<i>T<sub>c</sub></i> Superconduction Cylinder Using the Ferromagnetic Cylinder

Analysis of the magnetic distribution within a high-temperature superconductor magnetic shielding cylinder by use of the finite element method

Measurements of the magnetic noise spectra in HTS cylinders for magnetic shielding

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