Magnetic properties of finite superconducting cylinders. II. Nonuniform applied field and levitation force
Magnetic properties of finite superconducting cylinders. II. Nonuniform applied field and levitation force
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DOI：
10.1103/physrevb.64.214507
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发表时间：
2001-11
影响因子：
3.7
通讯作者：
C. Navau;Alvaro Sanchez
中科院分区：
文献类型：
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作者：
C. Navau;Alvaro Sanchez
本文研究了由均匀磁化的圆柱形永磁体产生轴对称磁场时，有限型ii超导圆柱体内部的电流穿透分布。结果是使用本系列第一篇论文中推导的一般框架得到的。对于超导体中临界电流恒定且临界电流与内部磁场呈指数关系的情况，根据电流分布计算出这种系统中的悬浮力。根据得到的结果，我们详细地研究了悬浮力与系统参数的关系。我们从结果中得出结论：(i)当磁体和超导体具有相似的尺寸时，悬浮力是优化的，（ii）超导体中过量的长度不会产生明显的力增加，以及（iii）退磁效应可以导致悬浮力的重要增强，特别是在薄膜的情况下，每单位体积的材料的力是最高的。
We study the current penetration profiles inside a finite type-II superconducting cylinder when it is in the presence of an axially symmetric applied field created by a cylindrical and uniformly magnetized permanent magnet. The results are obtained using the general framework derived in the first paper of this series. The levitation force in such a system is calculated from the current distribution, for the cases of a constant critical current in the superconductor and an exponential dependence of the critical current upon the internal magnetic field. From the obtained results, we study in detail how the levitation force depends upon the system parameters. We conclude from the results that (i) the levitation force is optimized when the magnet and the superconductor have similar dimensions, (ii) an excess of length in the superconductor can yield no significant increase in the force, and (iii) demagnetizing effects can lead to an important enhancement of the levitation force, particularly in the case of thin films, for which the force per unit volume of material is the highest.