Dadhich Anang, Pardo Enric
Institute of Electrical Engineering, Slovak Academy of Sciences, Bratislava, Slovakia.
Sci Rep. 2020 Nov 6;10(1):19265. doi: 10.1038/s41598-020-76221-z.
Superconducting stacks and bulks can act as very strong magnets (more than 17 T), but they lose their magnetization in the presence of alternating (or ripple) transverse magnetic fields, due to the dynamic magneto-resistance. This demagnetization is a major concern for applications requiring high run times, such as motors and generators, where ripple fields are of high amplitude and frequency. We have developed a numerical model based on dynamic magneto-resistance that is much faster than the conventional Power-Law-resistivity model, enabling us to simulate high number of cycles with the same accuracy. We simulate demagnetization behavior of superconducting stacks made of 10-100 tapes for up to 2 million cycles of applied ripple field. We found that for high number of cycles, the trapped field reaches non-zero stationary values for both superconducting bulks and stacks; as long as the ripple field amplitudes are below the parallel penetration field, being determined by the penetration field for a single tape in stacks. Bulks keep substantial stationary values for much higher ripple field amplitudes than the stacks, being relevant for high number of cycles. However, for low number of cycles, stacks lose much less magnetization as compared to bulks.
超导叠层和块材可以充当非常强的磁体（超过17特斯拉），但由于动态磁阻，它们在交变（或纹波）横向磁场存在时会失去磁化强度。这种去磁现象是诸如电动机和发电机等需要长时间运行的应用中的一个主要问题，在这些应用中，纹波磁场具有高幅度和高频率。我们基于动态磁阻开发了一个数值模型，该模型比传统的幂律电阻率模型快得多，使我们能够以相同的精度模拟大量的周期。我们模拟了由10至100根带材制成的超导叠层在施加高达200万个周期的纹波磁场时的去磁行为。我们发现，对于大量的周期，超导块材和叠层的俘获场都达到非零的稳定值；只要纹波磁场幅度低于平行穿透场，该平行穿透场由叠层中单个带材的穿透场决定。与叠层相比，块材在更高的纹波磁场幅度下能保持相当大的稳定值，这对于大量的周期来说是相关的。然而，对于少量的周期，与块材相比，叠层失去的磁化强度要少得多。
