Fiber-optic thermometry has the potential to provide rapid and reliable quench detection for emerging large-scale, high-field superconducting magnets fabricated with high-temperature-superconductor (HTS) cables. Developing non-voltage-based quench detection schemes, such as fiber Bragg grating (FBG) technology, are particularly important for applications such as magnetic fusion devices where a high degree of induced electromagnetic noise impose significant challenges on traditional voltage-based quench detection methods. To this end, two fiber optic quench detection techniques—FBG and ultra-long FBG (ULFBG)—were incorporated into two vacuum pressure impregnated, insulated, partially transposed, extruded, and roll-formed (VIPER) high-current HTS cables and tested in the SULTAN facility, which provides high-fidelity operating conditions to large-scale superconducting magnets. During surface heater induced quench-like events under a variety of operating conditions, FBG and ULFBG demonstrated strong signal-to-noise ratios (SNRs) ranging from 4 to 32 and measured single-digit temperature excursions; both the SNR and temperature sensitivity increase with temperature. Fiber thermal response times ranged between effectively instantaneous to a few seconds depending on the operating temperature. Strain sensitivity dominates the thermal sensitivity in the conditions achievable at SULTAN; however, measurements at higher quench evolution temperatures, coupled to future work to increase the thermal-to-strain signal, show promise for quench detection capability in full-scale magnets where temperature and strain may occur simultaneously. Overall, FBG and ULFBG were proven capable to quickly and reliably detect small temperature disturbances which induced quench initiation events for high current VIPER HTS conductors in realistic operating conditions, motivating further work to develop FBG and ULFGB quench detection systems for full-scale HTS magnets.

光纤测温法有可能为新兴的用高温超导体（HTS）电缆制造的大规模，高场超导磁体提供快速可靠的失超检测。开发诸如光纤布拉格光栅（FBG）之类的基于非电压的失超检测方案对于诸如磁融合设备等应用特别重要，在这些应用中，高度感应的电磁噪声对传统的基于电压的失超检测方法提出了重大挑战。为此，将两种光纤失超检测技术（FBG和超长FBG（ULFBG））结合到了两条真空压力浸渍，绝缘，部分转置，挤压和卷制成型（VIPER）的高电流HTS电缆中，并进行了测试在苏丹工厂，它为大型超导磁体提供了高保真工作条件。在各种操作条件下，表面加热器引发类似淬火的事件期间，FBG和ULFBG表现出强大的信噪比（SNR），范围从4到32，并且测量到的单位温度漂移；SNR和温度灵敏度都随温度而增加。光纤的热响应时间视操作温度而定，介于有效瞬时到几秒钟之间。在SULTAN可以达到的条件下，应变敏感性主导着热敏感性。然而，在更高的淬火扩展温度下进行的测量，再加上未来增加热应变信号的工作，显示出在可能同时发生温度和应变的全尺寸磁体中实现淬火检测能力的希望。