Dong Fangliang, Park Dongkeun, Lee Wooseung, Hao Luning, Huang Zhen, Bascuñán Juan, Jin Zhijian, Iwasa Yukikazu
Francis Bitter Magnet Laboratory/Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Gwangju Center, Korea Basic Science Institute, 77 Yongbong-ro, Buk-gu, Gwangju 61186, Korea.
Appl Phys Lett. 2022 Nov 7;121(19):194101. doi: 10.1063/5.0122493. Epub 2022 Nov 10.
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 REBaCuO (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.
在此，我们展示了一种预防性方法的实验和分析结果，该方法应用于无绝缘（NI）高温超导REBaCuO（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，至少是那些实验室规模的磁体，能够自我保护免于过热，因此也能免于失超，主要是因为NI特有的匝间电流旁路。然而，这些NI磁体确实会经历意外失超，例如，当由于上述故障模式现象导致通过磁体的电流突然下降时。在此，我们报告了传导冷却且在4.2 K下运行的NI REBCO线圈因突然放电触发失超的这一现象。我们还展示了针对此现象的预防性方法，该方法依赖于在线圈端子两端适当设计的分流电阻。通过该分流电阻，通过抑制失超起始的匝间热量和NI绕组内感应的过电流，防止了失超，并且线圈电流安全衰减。
