Superconducting joints are crucial for second generation high-temperature superconducting (2G HTS) closed-loop coils that work in the persistent current mode (PCM) operation. Here, we report an efficient approach for superconducting joints of YBa₂Cu₃O_7-σ (YBCO) coated conductors (CCs). The YBCO layer is etched to and from some microchannels, which serve as oxygen diffusion paths during oxygenation annealing (OA), to accelerate the recovery of critical current (I _c) of the joined two YBCO layers. The I _c of the superconducting joint is 118 A at 77 K with an optimized joining temperature and a short OA time (10 h), which is about 82% I _c of the joined YBCO CCs. The persistent field decay of the closed-loop coil shows a joint resistance (R _j) of less than 2.2 × 10⁻¹³ Ω at 77 K. Two YBCO films epitaxially grown along the c-axis diffuse into each other at the interface and form a dense joining, enabling superconducting current path. This superconducting joint technique can promote the achievement of the PCM operation in 2G HTS magnet applications, such as magnetic resonance imaging and nuclear magnetic resonance.

中文翻译：

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YBCO涂层导体超导接头的有效方法

超导接头对于以持续电流模式 (PCM) 运行的第二代高温超导 (2G HTS) 闭环线圈至关重要。_{在这里，我们报告了 YBa 2} Cu ₃ O _7-超导接头的有效方法_σ (YBCO) 涂层导体 (CC)。YBCO层被蚀刻进出一些微通道，这些微通道在氧化退火（OA）期间充当氧扩散路径，以加速临界电流的恢复（我 _c ) 连接的两个 YBCO 层。这我 _{超导接头的c}在 77 K 时为 118 A，具有优化的连接温度和较短的 OA 时间（10 小时），约为 82%我 _c加入的 YBCO CC。闭环线圈的持续场衰减显示出联合电阻（R _j ) 在 77 K 时小于 2.2 × 10 ^-13 Ω。两个 YBCO 薄膜沿外延生长C轴在界面处相互扩散并形成致密连接，从而实现超导电流路径。这种超导联合技术可以促进PCM操作在2G HTS磁体应用中的实现，例如磁共振成像和核磁共振。