Voltage-ampere characteristics of YBCO coated conductor under inhomogeneous oscillating magnetic field
Voltage-ampere characteristics of YBCO coated conductor under inhomogeneous oscillating magnetic field
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DOI：
10.1063/1.4955266
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发表时间：
2016-06-27
影响因子：
4
通讯作者：
Coombs, T. A.
中科院分区：
文献类型：
--
作者：
Geng, J.;Shen, B.;Coombs, T. A.
当直流载流第二类超导体受到垂直于电流方向的振荡磁场时，表现出动态电阻。如果超导体处于高量级的均匀电场中，其动态阻值几乎与输运电流无关。访问数/每百万人：Reach for[Hoffmann et al.APPL超级棒。然而，21,1628(2011)]发现，当超导磁带处于与旋转磁铁产生的磁带表面垂直的非均匀磁场下时，磁通泵浦效应。根据他们的工作，我们报道了YBCO涂层导体在不同频率和方向旋转的永磁体作用下的全伏安(V-I)曲线。我们发现，当输运电流小于临界电流时，相反旋转方向下的两条曲线始终存在差异，而当输运电流超过临界值后，差异逐渐减小。我们还发现，对于不同的场频，两条曲线之间的差异随着场频的降低而减小得更快。结果表明，输运损耗依赖于输运电流和磁场行进的相对方向，这与传统的动态电阻模型不同。该工作对超导电机的设计具有一定的指导意义。由AIP出版公司出版。
Direct current carrying type II superconductors present a dynamic resistance when subjected to an oscillating magnetic field perpendicular to the current direction. If a superconductor is under a homogeneous field with high magnitude, the dynamic resistance value is nearly independent of transport current. Hoffmann and coworkers [Hoffmann et al., IEEE Trans. Appl. Supercond. 21, 1628 (2011)] discovered, however, flux pumping effect when a superconducting tape is under an inhomogeneous field orthogonal to the tape surface generated by rotating magnets. Following their work, we report the whole Voltage-Ampere (V-I) curves of an YBCO coated conductor under permanent magnets rotating with different frequencies and directions. We discovered that the two curves under opposite rotating directions differ from each other constantly when the transport current is less than the critical current, whereas the difference gradually reduces after the transport current exceeds the critical value. We also find that for different field frequencies, the difference between the two curves decreases faster with lower field frequency. The result indicates that the transport loss is dependent on the relative direction of the transport current and field travelling, which is distinct from traditional dynamic resistance model. The work may be instructive for the design of superconducting motors. Published by AIP Publishing.