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Chiang, C. H.; Yang, Cheng‐Ta; Hsieh, Ping-Cheng; Chan, And W. C.

doi:10.1023/a:1022925419581

Cited by 22 publications

(3 citation statements)

References 2 publications

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“…Up to now, the vertical levitation force relaxation in a symmetrical system was the main focus of interest, however there are few reports about the levitation force relaxation and guidance force relaxation in an unsymmetrical levitation system. In addition, the levitation and lateral force between a permanent magnet and a high-temperature superconductor have been investigated by many experimental measurements [13][14][15][16][17][18][19] and theoretical simulations [20][21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Relaxation properties of magnetic force between a magnet and superconductor in an unsymmetrical levitation system

Zhang

Zhou

et al. 2009

Supercond. Sci. Technol.

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We present an experimental study of the relaxation of vertical and horizontal force components in an unsymmetrical high-temperature superconducting levitation system, with different initial cooling processes, after fixing the levitated body statically in a given position. It was found that the values of the relaxation measurements of the levitation force and lateral force remained constant or increased with time after vertical and horizontal traverses. The phenomenon has been theoretically described based on the Bean model and the thermally activated flux creep theory. The criterion developed in the present work is considered to be suitable for providing qualitative predictions of the relaxation properties in the levitation force and lateral force.

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Section: Introductionmentioning

confidence: 99%

Relaxation properties of magnetic force between a magnet and superconductor in an unsymmetrical levitation system

Zhang

Zhou

et al. 2009

Supercond. Sci. Technol.

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“…Under these conditions, the boiling temperature of the liquid nitrogen (LN 2 ) coolant reduces, which, in turn, reduces the evaporation rate of the liquid nitrogen cryogen, thus extending the operation time of the HTS Maglev vehicle [12]. It is well known that the change in operating temperature also directly influences the Maglev performance of the bulk superconductors [13][14][15]. In previous work based on the HTS Maglev-ETT test system, the influence of low ambient pressure on the levitation force and force relaxation of Y-Ba-Cu-O (YBCO) single grain bulk superconductors was investigated and found to improve the levitation force significantly [16,17], as well as the guidance force when the field-cooling height (FCH) is lower than 35 mm [18].…”

Section: Introductionmentioning

confidence: 99%

Magnetic levitation and guidance performance of Y–Ba–Cu–O and Gd–Ba–Cu–O bulk superconductors under low ambient pressure

Zhang¹,

Deng²,

Zhang³

et al. 2019

J. Phys. D: Appl. Phys.

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The high-temperature superconducting Maglev-evacuated tube transport (HTS Maglev-ETT) system has significant potential for practical applications. In order to employ HTS bulks in an ETT system, it is necessary to study the magnetic levitation and guidance performance of bulk superconductors under low ambient pressure conditions that are representative of those inside the tube. As a result, we have investigated the Maglev performance of Y–Ba–Cu–O (YBCO) and Gd–Ba–Cu–O (GdBCO) single grain, bulk superconductors under different ambient pressures of 100 kPa, 60 kPa and 20 kPa using a bespoke pressure-controlling platform, in which the superconductors were positioned above a Halbach permanent magnet guideway. The levitation forces under conditions of field-cooling (FC) and zero-field-cooling (ZFC) have been measured and analyzed. The guidance force for the FC case and the levitation force relaxation for the ZFC case were also measured. It was found from the experimental results that the Maglev performance of both types of bulk superconductor improves significantly by reducing the ambient pressure in their immediate working environment. The levitation forces of YBCO and GdBCO bulk superconductors were observed to increase by 11.6% and 4.4% in the case of FC, and by 20.3% and 13.7% in the case of ZFC, respectively, as the ambient pressure changed from 100 kPa to 20 kPa. An improvement of the guidance force and an inhibition of the levitation force relaxation were also observed for these materials. The supercooled liquid nitrogen cryogen in the low-pressure environment further reduces the temperature, which, in turn, increases the critical current density Jc of the bulk superconductors and improves their levitation performance. These results provide further evidence of the significant advantages of combining HTS Maglev with evacuated tube technologies as a key enabling feature of the HTS Maglev-ETT system. The data further indicate that YBCO bulk superconductors tend to be more sensitive to ambient pressure and temperature variation than GdBCO bulk superconductors. This difference essentially reflects the dependence of Maglev performance of HTS bulk superconductors on Jc when operating in a low-pressure environment.

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“…But up to now, there are only a few reports available on the crossing phenomenon in the force-distance hysteretic curve. Moreover, it is well known that the levitation force between a superconductor and a magnet is not only related to the electromagnetic properties of the superconductor, but also to the thickness and shape of the samples [14], initial cooling process [15,16], operating temperature [17], grain-orientation [18] etc. Postrekhin et al [19] reported the dependence of the levitation force on the average speed of moving the magnet (up to 12 mm/s) towards the superconductor and found that the maximum levitation force increased with increase in the moving speed of the magnet.…”

Section: Introductionmentioning

confidence: 99%

Experimental observation of a crossing in the force–displacement hysteretic curve of a melt processed YBaCuO bulk superconductor

Zhang

Zhou

2008

Physica C: Superconductivity

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Cited by 22 publications

References 2 publications

Relaxation properties of magnetic force between a magnet and superconductor in an unsymmetrical levitation system

Relaxation properties of magnetic force between a magnet and superconductor in an unsymmetrical levitation system

Magnetic levitation and guidance performance of Y–Ba–Cu–O and Gd–Ba–Cu–O bulk superconductors under low ambient pressure

Experimental observation of a crossing in the force–displacement hysteretic curve of a melt processed YBaCuO bulk superconductor

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