Here, we present experimental and analytical results of a preventive approach applied to a fault-mode phenomenon caused by electrodes or power-source failure in a no-insulation (NI) high-temperature superconducting REBa2Cu3O7−x (REBCO, RE = rare earth) magnet. It is generally agreed that the NI magnets, at least those of laboratory scale, are self-protected from overheating and, therefore, from quenching, chiefly because of turn-to-turn current bypassing unique to NI. However, these NI magnets do experience unexpected quenches, e.g., when the current through the magnet suddenly drops due to the aforementioned fault-mode phenomenon. Here, we report this phenomenon of a sudden-discharging-triggered quench of an NI REBCO coil, conduction-cooled, and operated at 4.2 K. We also present our preventive approach for this phenomenon that relies on an appropriately designed resistor shunted across the coil terminals. With this shunt resistor, a quench was prevented by suppressing the quench initiating turn-to-turn heat and induced overcurrent within the NI winding, and the coil current decayed safely.
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机译：在这里，我们介绍了一种预防方法的实验和分析结果，该方法应用于无绝缘 （NI） 高温超导 REBa2Cu3O7−x（REBCO，RE = 稀土）磁体中由电极或电源故障引起的故障模式现象。人们普遍认为，NI 磁体，至少是实验室规模的磁体，具有自我保护功能，可防止过热，因此不会发生淬火，这主要是由于 NI 独有的匝间电流旁路。然而，这些 NI 磁体确实会经历意外的淬火，例如，由于上述故障模式现象，通过磁体的电流突然下降。在这里，我们报告了 NI REBCO 线圈突然放电触发的失超现象，传导冷却，并在 4.2 K 下运行。我们还提出了针对这种现象的预防方法，该方法依赖于在线圈端子上分流的适当设计的电阻器。使用这种分流电阻器，通过抑制在 NI 绕组内引发匝间加热和感应过电流的淬火来防止失安，并且线圈电流安全地衰减。
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