SPARC is being designed to operate with a normalized beta of $\beta _N=1.0$ , a normalized density of $n_G=0.37$ and a safety factor of $q_{95}\approx 3.4$ , providing a comfortable margin to their respective disruption limits. Further, a low beta poloidal $\beta _p=0.19$ at the safety factor $q=2$ surface reduces the drive for neoclassical tearing modes, which together with a frozen-in classically stable current profile might allow access to a robustly tearing-free operating space. Although the inherent stability is expected to reduce the frequency of disruptions, the disruption loading is comparable to and in some cases higher than that of ITER. The machine is being designed to withstand the predicted unmitigated axisymmetric halo current forces up to 50 MN and similarly large loads from eddy currents forced to flow poloidally in the vacuum vessel. Runaway electron (RE) simulations using GO+CODE show high flattop-to-RE current conversions in the absence of seed losses, although NIMROD modelling predicts losses of ${\sim }80$ %; self-consistent modelling is ongoing. A passive RE mitigation coil designed to drive stochastic RE losses is being considered and COMSOL modelling predicts peak normalized fields at the plasma of order $10^{-2}$ that rises linearly with a change in the plasma current. Massive material injection is planned to reduce the disruption loading. A data-driven approach to predict an oncoming disruption and trigger mitigation is discussed.

中文翻译：

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SPARC 托卡马克的 MHD 稳定性和中断

SPARC 被设计为使用标准化的 beta 运行 $\beta _N=1.0$ ，归一化密度 $n_G=0.37$ 和一个安全系数 $q_{95}\约 3.4$ ，为各自的中断限制提供了舒适的余量。此外，低β极向 $\beta _p=0.19$ 在安全系数 $q=2$ 表面减少了对新古典撕裂模式的驱动，这与冻结的经典稳定电流分布一起可能允许访问稳健的无撕裂操作空间。尽管预期固有稳定性会降低中断频率，但中断负荷与 ITER 相当，在某些情况下甚至高于 ITER。该机器的设计旨在承受高达 50 MN 的预计未经缓解的轴对称晕流力以及来自被迫在真空容器中极向流动的涡流的类似大负载。使用 GO+CODE 的失控电子 (RE) 模拟显示在没有种子损失的情况下具有较高的平顶到 RE 电流转换，尽管 NIMROD 建模预测 ${\sim }80$ %; 自洽建模正在进行中。正在考虑设计用于驱动随机 RE 损耗的无源 RE 缓解线圈，COMSOL 建模预测有序等离子体处的峰值归一化场 $10^{-2}$ 随着等离子体电流的变化线性上升。计划进行大量材料注入以减少中断负荷。讨论了一种预测即将到来的中断和触发缓解的数据驱动方法。