Dynamic resistance of a high-Tc coated conductor wire in a perpendicular magnetic field at 77K
Dynamic resistance of a high-Tc coated conductor wire in a perpendicular magnetic field at 77K
复制标题
DOI：
10.1088/1361-6668/aa54e5
复制
发表时间：
2017-03-01
影响因子：
3.6
通讯作者：
Bumby, Chris W.
中科院分区：
文献类型：
--
作者：
Jiang, Zhenan;Toyomoto, Ryuki;Bumby, Chris W.
超导高 T-c 涂层导体 (CC) 线由大纵横比的陶瓷薄膜组成。当暴露于交变磁场时，这种几何形状会导致显着的耗散损耗。在这里，我们报告了市售 SuperPower 和 Fujikura CC 电线在交流垂直场中“动态电阻”的实验测量结果。动态电阻的开始发生在阈值场幅度处，该阈值场幅度由总直流传输电流和导体的穿透场决定。我们表明，归一化磁化损耗的场依赖性为零传输电流时的阈值场提供了明确的值。根据这一见解，我们获得了垂直场动态电阻的表达式。这种方法意味着动态电阻和施加场幅度之间以及阈值场和传输电流之间存在线性关系，这与我们的实验数据一致。获得的解析表达式产生的值与在各种频率和传输电流下获得的测量结果非常一致，并且对于不同电线制造商生产的具有显着不同尺寸和临界电流的多条 CC 电线而言。我们进一步表明，在高传输电流下，测量的直流电阻包括一个额外的非线性项，这是由于直流传输电流引起的磁通流电阻所致。一旦导线的场相关临界电流在每个场周期的一部分低于直流传输电流，就会发生这种情况。我们的结果提供了一种有效且简单的方法来计算 CC 线的动态电阻，电流和磁场大小与超导机器中预期的一致。
Superconducting high-T-c coated conductor (CC) wires comprise a ceramic thin film with a large aspect ratio. This geometry can lead to significant dissipative losses when exposed to an alternating magnetic field. Here we report experimental measurements of the 'dynamic resistance' of commercially available SuperPower and Fujikura CC wires in an AC perpendicular field. The onset of dynamic resistance occurs at a threshold field amplitude, which is determined by the total DC transport current and the penetration field of the conductor. We show that the field-dependence of the normalised magnetisation loss provides an unambiguous value for this threshold field at zero transport current. From this insight we then obtain an expression for the dynamic resistance in perpendicular field. This approach implies a linear relationship between dynamic resistance and applied field amplitude, and also between threshold field and transport current and this is consistent with our experimental data. The analytical expression obtained yields values that closely agree with measurements obtained across a wide range of frequencies and transport currents, and for multiple CC wires produced by different wire manufacturers and with significantly differing dimensions and critical currents. We further show that at high transport currents, the measured DC resistance includes an additional nonlinear term which is due to flux-flow resistance incurred by the DC transport current. This occurs once the field-dependent critical current of the wire falls below the DC transport current for part of each field cycle. Our results provide an effective and simple approach to calculating the dynamic resistance of a CC wire, at current and field magnitudes consistent with those expected in superconducting machines.