Critical State of YBCO Superconductors With Artificially Patterned Holes

Bartolomé, Elena; Granados, X.; Puig, T.; Obrados, X.; Reddy, E. Sudhakar; Kračunovska, S.

doi:10.1109/tasc.2005.848210

Cited by 21 publications

(16 citation statements)

References 11 publications

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“…Analytical and numerical calculations are in good agreement. We observe that ∆M/|M 0 | increases with the radius of the hole, as expected intuitively and illustrated in Hall probe mapping experiments [20]. As shown in Appendix A, a series expansion of the analytical result for the magnetization drop around R = 0 yields…”

Section: Influence Of the Hole Radius On The Magnetization Dropsupporting

confidence: 82%

“…For bulk samples, studies based on the Bean model already pointed to the magnetization drop that results from drilling holes [20]. It was also shown that for a given lattice, the magnetization drop increases with the diameter of the holes [20,21]. It has been measured in [21] that increasing the hole diameter by a factor of 2 results in a magnetization drop of ∼ 80%.…”

Section: Introductionmentioning

confidence: 99%

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Bulk high-T_csuperconductors with drilled holes: how to arrange the holes to maximize the trapped magnetic flux?

Lousberg

Ausloos

Vanderbemden

et al. 2008

Supercond. Sci. Technol.

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Abstract. Drilling holes in a bulk high-Tc superconductor enhances the oxygen annealing and the heat exchange with the cooling liquid. However, drilling holes also reduces the amount of magnetic flux that can be trapped in the sample. In this paper, we use the Bean model to study the magnetization and the current line distribution in drilled samples, as a function of the hole positions. A single hole perturbs the critical current flow over an extended region that is bounded by a discontinuity line, where the direction of the current density changes abruptly. We demonstrate that the trapped magnetic flux is maximized if the center of each hole is positioned on one of the discontinuity lines produced by the neighbouring holes. For a cylindrical sample, we construct a polar triangular hole pattern that exploits this principle; in such a lattice, the trapped field is ∼ 20% higher than in a squared lattice, for which the holes do not lie on discontinuity lines. This result indicates that one can simultaneously enhance the oxygen annealing, the heat transfer, and maximize the trapped field.

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Section: Influence Of the Hole Radius On The Magnetization Dropsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Bulk high-T_csuperconductors with drilled holes: how to arrange the holes to maximize the trapped magnetic flux?

Lousberg

Ausloos

Vanderbemden

et al. 2008

Supercond. Sci. Technol.

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“…As seen in Fig. 6c, the average trapped field is even increasing as the number and size of holes are increased chiefly owing to the weaker trapped field strength and larger J c in equation (5). So the primary reason of the total trapped flux reduction in Fig.…”

Section: Discussionmentioning

confidence: 88%

“…Therefore a number of researches have been carried out to improve the mechanical properties of melt textured YBCO. Recently it has been proposed to drill arrays of artificial holes within high temperature superconducting bulk in order to improve their chemical and thermal properties [1][2][3][4][5][6]. The results of the researches have proved that the artificial holes prevented the fracture of HTS bulk by thermal and magnetic stress during cool-down or magnetization.…”

Section: Introductionmentioning

confidence: 99%

Trapped Field Analysis of a High Temperature Superconducting Bulk with Artificial Holes

Jang¹,

man-soo²,

Han³

et al. 2011

Journal of Magnetics

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To improve trapped field characteristics of a high temperature superconducting (HTS) bulk, a technique to implement artificial holes has been studied. The artificial holes, filled up with epoxy or metal, may provide better cooling channel and enhance mechanical strength of the HTS bulk. Although many useful researches based on experiments have been reported, a numerical approach is still limited because of several reasons that include: 1) highly non-linear electromagnetic properties of HTS; and 2) difficulty in modeling of randomly scattered "small" artificial holes. In this paper, a 2-D finite element method with iteration is adopted to analyze trapped field characteristics of HTS bulk with artificial holes. The validity of the calculation is verified by comparison between measurement and calculation of a trapped field in a 40 × 40 mm square and 3.1 mm thick HTS bulk having 16 artificial holes with diameter of 0.7 mm. The effects of sizes and array patterns of artificial holes on distribution of trapped field within HTS bulk are numerically investigated using suggested method.

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“…In the literature, although it is has been already demonstrated that drilling holes in a sample decreases its trapped flux [14,15], no experimental study has been reported so far about the influence of the hole pattern on the trapping properties of drilled samples. The purpose of this paper is to show experimentally that, considering a given number of identical holes, their geometrical arrangement has an influence on the maximum trapped flux density.…”

Section: Introductionmentioning

confidence: 99%

Modification of the trapped field in bulk high-temperature superconductors as a result of the drilling of a pattern of artificial columnar holes

Lousberg¹,

Fagnard²,

Ausloos³

et al. 2010

J. Phys.: Conf. Ser.

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Abstract. The trapped magnetic field is examined in bulk high-temperature superconductors that are artificially drilled along their c-axis. The influence of the hole pattern on the magnetization is studied and compared by means of numerical models and Hall probe mapping techniques. To this aim, we consider two bulk YBCO samples with a rectangular cross-section that are drilled each by six holes arranged either on a rectangular lattice (sample I) or on a centered rectangular lattice (sample II). For the numerical analysis, three different models are considered for calculating the trapped flux: (i), a two-dimensional (2D) Bean model neglecting demagnetizing effects and flux creep, (ii), a 2D finite-element model neglecting demagnetizing effects but incorporating magnetic relaxation in the form of an E − J power law, and, (iii), a 3D finite element analysis that takes into account both the finite height of the sample and flux creep effects. For the experimental analysis, the trapped magnetic flux density is measured above the sample surface by Hall probe mapping performed before and after the drilling process. The maximum trapped flux density in the drilled samples is found to be smaller than that in the plain samples. The smallest magnetization drop is found for sample II, with the centered rectangular lattice. This result is confirmed by the numerical models. In each sample, the relative drops that are calculated independently with the three different models are in good agreement. As observed experimentally, the magnetization drop calculated in the sample II is the smallest one and its relative value is comparable to the measured one. By contrast, the measured magnetization drop in sample (1) is much larger than that predicted by the simulations, most likely because of a change of the microstructure during the drilling process.

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Critical State of YBCO Superconductors With Artificially Patterned Holes

Cited by 21 publications

References 11 publications

Bulk high-T_csuperconductors with drilled holes: how to arrange the holes to maximize the trapped magnetic flux?

Bulk high-T_csuperconductors with drilled holes: how to arrange the holes to maximize the trapped magnetic flux?

Trapped Field Analysis of a High Temperature Superconducting Bulk with Artificial Holes

Modification of the trapped field in bulk high-temperature superconductors as a result of the drilling of a pattern of artificial columnar holes

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Critical State of YBCO Superconductors With Artificially Patterned Holes

Cited by 21 publications

References 11 publications

Bulk high-Tcsuperconductors with drilled holes: how to arrange the holes to maximize the trapped magnetic flux?

Bulk high-Tcsuperconductors with drilled holes: how to arrange the holes to maximize the trapped magnetic flux?

Trapped Field Analysis of a High Temperature Superconducting Bulk with Artificial Holes

Modification of the trapped field in bulk high-temperature superconductors as a result of the drilling of a pattern of artificial columnar holes

Contact Info

Product

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About

Bulk high-T_csuperconductors with drilled holes: how to arrange the holes to maximize the trapped magnetic flux?

Bulk high-T_csuperconductors with drilled holes: how to arrange the holes to maximize the trapped magnetic flux?