• Title, Summary, Keyword: Magnetic levitation

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Development of a Cost-Effective Process for the Fabrication of Single Grain $YBa_2Cu_3O_{7-y}$ Bulk Superconductors (단결정 $YBa_2Cu_3O_{7-y}$ 벌크 초전도체 제조를 위한 경제적 공정의 개발)

  • Park, Soon-Dong;Kim, Kwang-Mo;Jun, Byung-Hyuk;Han, Young-Hee;Kim, Chan-Joong
    • Progress in Superconductivity
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    • v.13 no.2
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    • pp.133-138
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    • 2011
  • To reduce the processing cost of the single grain REBCO (RE: Rare-earth elements) bulk superconductors, a cost-effective process should be developed. One possible way of developing the cost-effective process is the use of low-cost precursor powders. In this study, the single grain YBCO superconductors were fabricated using a home made powder. $YBa_2Cu_3O_{7-y}$ (Y123) powders were synthesized at $850-900^{\circ}C$ in air by the powder calcination method with repeated crushing and heat treatment steps. The processing parameters for the fabrication of single grain Y123 bulk superconductors, $T_{max}$ (maximum temperature), $T_p$ (peritectic temperature) and a cooling rate through $T_p$ were optimized. To enhance the flux pinning capacity of the single grain Y123 samples, $Y_2BaCuO_5$ (Y211) particles were dispersed in the Y123 matrix by adding $Y_2O_3$ powder to the calcined Y123 powder. Applying the optimized processing condition, the single grain Y123 superconductors with $T_c=91\;K$ and $J_c=1.5{\times}10^4\;A/cm^2$ at 2 T were successfully fabricated using a home made powder. The levitation forces and trapped magnetic field at 77 K measured using a Nd-B-Fe permanent magnet of 5300 G were 47 N and 3000 G, respectively, which are comparable to those obtained for the samples fabricated using a commercial grade Y123 powders.

Optimal Design of Permanent Magnet Thrust Bearings (영구자석형 스러스트 베어링의 최적 설계)

  • Yoo, Seong-Yeol;Kim, Woo-Yeon;Kim, Seung-Jong;Lee, Wook-Ryun;Bae, Yong-Chae;Noh, Myoung-Gyu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.4
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    • pp.353-358
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    • 2011
  • In this paper, we describe a process for optimally designing a ring-type permanent magnet thrust bearing. The bearing consists of two sets of permanent magnet rings. One set is located inside the other set. An axial offset between the two sets creates axial force, which results in a thrust bearing function. In order to realize an optimal design of the bearing where the required load capacity of the bearing is achieved with the least magnet volume, we derived analytical design equations by adopting the equivalent current sheet (ECS) method. We considered the following two types of magnet arrays: axial arrays and Halbach arrays. These two types of arrays are optimized using the analytical design equations. The results of the optimization are verified using three dimensional (3D) finite element analyses (FEA). The results show that the Halbach array can achieve the required load capacity with less amount of permanent magnet than the axial array does. The efficacy of the ECS method is also verified by using 3D FEA. It is found that the accuracy of ECS method is more sensitive to the underlying assumptions for the Halbach array than for the axial array.