Kapolka M, Ruiz H S
School of Engineering and Space Park Leicester, University of Leicester, University Rd, Leicester, LE1 7RH UK.
Sci Rep. 2022 Apr 29;12(1):7030. doi: 10.1038/s41598-022-10728-5.
When compared with rare-earth coated conductors, magnesium diboride superconducting cables are known to show significant advantages by cost and easy production. However, the inherent difficulty for achieving a significant reduction of their magnetization losses in multifilamentary wires, without degrading the high critical current density that is so characteristic of the monowire, is considered as one of the major drawbacks for their practical use in high power density applications. Being this one of the major markets for superconducting cables, from fundamental principles and computational optimization techniques, in this paper we demonstrate how the embedding of the superconducting filaments into soft-ferromagnetic metastructures can render to their full magnetic decoupling, and therefore, to the maximum reduction of the energy losses that can be achieved without deteriorate the critical current density of the cable. The designed multifilamentary metastructure is made of NbTi coated MgB superconducting filaments in a Cu-matrix, serving as a reference for validating our model with actual experimental measurements in monowires and multifilamentary wires. The novelty in our computationally aided multifilamentary wires, is that each one of the filaments is embedded within a thin metastructure made of a soft-ferromagnetic layer and a resistive layer. We have found that for soft-ferromagnetic layers with magnetic permeabilities in the range of [Formula: see text] 20-100, nearly a full magnetic decoupling between the superconducting filaments can be achieved, leading to efficiencies higher than [Formula: see text], and an overall reduction of the AC-losses (including eddy currents at the Cu-matrix) higher than [Formula: see text].
与稀土涂层导体相比，已知二硼化镁超导电缆在成本和易于生产方面具有显著优势。然而，在多丝导线中实现其磁化损耗显著降低而又不降低单丝所特有的高临界电流密度这一固有难题，被认为是其在高功率密度应用中实际应用的主要缺点之一。作为超导电缆的主要市场之一，从基本原理和计算优化技术出发，在本文中我们展示了将超导细丝嵌入软铁磁亚结构如何能实现其完全磁解耦，从而在不降低电缆临界电流密度的情况下最大程度地降低能量损耗。所设计的多丝亚结构由铜基体中包覆铌钛的二硼化镁超导细丝组成，用作通过单丝和多丝导线的实际实验测量来验证我们模型的参考。我们的计算辅助多丝导线的新颖之处在于，每根细丝都嵌入在由软铁磁层和电阻层组成的薄亚结构中。我们发现，对于磁导率在20 - 100范围内的软铁磁层，超导细丝之间几乎可以实现完全磁解耦，效率高于[公式：见原文]，并且交流损耗（包括铜基体中的涡流）总体降低高于[公式：见原文]。
