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中间氧化物阻障来开发具有低交流损耗的Ag护套Bi基（Bi 2223）高Tc超导线材。为了抑制对Bi_（2223）超导体的相形成和性能的副作用，选用Ca_2CuO_3（CCO）和SrZrO_3（SZO）作为阻挡层材料。从检查的传输性能和横向矩阵电阻率，SZO被发现是更有效地抑制临界电流密度（Jc）的恶化，也抑制了交流外场下的干扰电磁耦合。最后，在77 K时，Jc约为20 kAcm-2，自场和耦合频率fc在77 K时为270 Hz，外加场垂直于带材宽面。根据这些成就，屏障带在50 Hz附近的垂直场损耗比具有完全耦合灯丝的常规4 mm宽带的垂直场损耗低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.