Design and Development of Ag-Sheathed Bi-Based High-Tc Superconducting Wires with Low AC Losses by Introducing Oxide Resistive Barriers

本研究的目的是通过引入丝间氧化物电阻屏障，开发银护层铋基（Bi2223）低交流损耗的高tc超导线。为了抑制对Bi2223超导体相形成和性能的副作用，选择了Ca2CuO3 （CCO）和SrZrO3 （SZO）作为阻挡材料。从输运特性和横向基体电阻率的测试中发现，SZO更有效地抑制了交流外场下临界电流密度（Jc）的恶化，并抑制了丝间电磁耦合。最后，在77 K条件下，Jc约为20 kAcm-2，自场和耦合频率fc在77 K条件下为270 Hz，与垂直于胶带宽面的交流外场同时实现。根据这些成果，势垒带在50 Hz左右的垂直场损耗比具有完全耦合细丝的传统4 mm宽带低70-80%。

The aim of this study is development of Ag-sheathed Bi-based (Bi2223) high-Tc superconducting wires with low-AC loss by introducing interfilamentary oxide resistive barriers. In order to suppress the side effect on the phase formation and properties of Bi2223 superconductor, Ca2CuO3 (CCO) and SrZrO3 (SZO) were selected as barrier materials. From the examination of transport properties and transverse matrix resistivity, SZO was found to be more effective to suppress the deterioration of critical current density (Jc) and also to suppress the interfilamentary electromagnetic coupling under an AC external field. Finally, Jc around 20 kAcm-2 at 77 K and self-field and coupling frequency fc of 270 Hz at 77 K and AC external field perpendicular to the broader face of tape could be achieved simultaneously. According to these achievements, perpendicular field losses around 50 Hz for barrier tape were 70-80% lower than those for conventional 4 mm-width tape with fully coupled filaments.