Mitigation of Demagnetization of Bulk Superconductors by Time-Varying External Magnetic Fields
Mitigation of Demagnetization of Bulk Superconductors by Time-Varying External Magnetic Fields
复制标题
时变外部磁场减轻体超导体的退磁
DOI：
10.1109/tasc.2016.2525820
复制
发表时间：
2016
影响因子：
1.8
通讯作者：
D. Cardwell
中科院分区：
文献类型：
--
作者：
J. Zou;M. Ainslie;D. Hu;D. Cardwell
大型单晶粒高温超导块材在各种工程应用中具有替代永磁体的巨大潜力。然而，基于我们先前的研究，当块材受到时变外磁场时，块材超导体中的俘获场会被衰减甚至擦除。因此，重要的是开发一种方法，以保护块从退磁，通过提高块的热传导和/或减少交流损耗。改进块材的热传导涉及材料制造工艺的改进，这可能对其超导性能产生不利影响。在大块周围使用屏蔽材料有助于减少交流损耗，但也提供了一种持久的方式来保持原始材料的特性。在本文中，提出了两种屏蔽的情况下，并进行了数值评估：环形屏蔽铜线圈和表面屏蔽铁磁材料。基于数值模拟结果，环形线圈工作良好的外部施加的交流场的幅度较大，频率较高。然而，铁磁材料对于相对较低的场的表面屏蔽是优选的。最后，提出了一种优化的屏蔽设计。
Large single-grain high-temperature superconducting bulks have significant potential to replace permanent magnets in various engineering applications. However, based on our previous research, the trapped field in a bulk superconductor can be attenuated or even erased when a bulk is subjected to a time-varying external magnetic field. Therefore, it is important to develop a method to protect bulks from demagnetization by improving the thermal conduction of the bulk and/or reducing ac losses. Improvement in the thermal conduction of bulks involves modification of the material fabrication process, which may have a detrimental effect on its superconducting properties. Employing shielding materials around a bulk helps to decrease the ac losses, but also provides a durable way to maintain the original material properties. In this paper, two shielding cases are proposed and evaluated numerically: ring-shaped shielding with a copper coil and surface shielding with a ferromagnetic material. Based on the numerical modeling results, the ring-shaped coil works well for externally applied ac fields of larger magnitude and higher frequency. However, the ferromagnetic material was preferable for surface shielding for relatively lower fields. Finally, an optimal shield design is presented.
影响因子：
3.6
作者：
Durrell, J. H.;Dennis, A. R.;Cardwell, D. A.
通讯作者：
Cardwell, D. A.