类ARC托卡马克的稳态、核心与运行优化：通过等离子体成分和形状
Steady state, core, operational optimization of an ARC-like tokamak via plasma composition and shape
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中文总结 AI 辅助
本研究采用贝叶斯优化方法，对类ARC托卡马克的等离子体成分与形状等参数进行稳态运行优化，提升了聚变功率与功率密度，该方法可推广至其他托卡马克。
中文摘要 AI 辅助
杂质成分、等离子体形状以及台基密度都是影响聚变功率的重要调控手段。本研究探究这些参数的变化对聚变功率的影响方式，并旨在找到这些参数的最优值。这些变量的关键影响途径包括改变核心湍流输运、燃料组分密度、台基压力以及等离子体体积；研究观察到，杂质含量增加会引发离子温度梯度（ITG）模式的稳定化。所有这些参数对台基压力的依赖关系尤为复杂，因为台基压力会分别对 peeling 模式和 ballooning 模式产生影响，而这两种模式均会限制台基性能。本研究采用贝叶斯优化方法实现了该多维运行空间的优化，得到了与ARC V3A类似的运行点，其聚变功率提升约30%，聚变功率密度更高；增加拉长比、三角性、方形度等形状参数，以及高Zeff（有效电荷数）均有利于提升性能。当允许拉长比也变化时，聚变功率可提升约65%。研究还发现，方形度虽未被普遍关注，却是影响聚变功率的重要调控手段；等离子体性能受限于Greenwald密度极限约束。本研究开发的工作流程以ARC V3A为例进行了验证，可便捷应用于其他托卡马克设计。
英文摘要
Impurity composition, plasma shape, and pedestal density all provide strong levers on fusion power. Here, we explore the ways in which their variation changes fusion power and seek to find the optimum of these parameters. The key impacts of these variables are through changes in the core turbulent transport, the density of the fuel species, the pedestal pressure, and the plasma volume. ITG stabilization due to increased amounts of impurities is observed. The dependence of all of these parameters on the pedestal pressure is especially complicated because of the separate impacts on the peeling and ballooning modes, which can each limit the pedestal. Optimization of this multidimensional operating space is enabled by the use of Bayesian optimization, resulting in an operating point similar to ARC V3A with ~30% more fusion power and a higher fusion power density. Increased shaping parameters, including elongation, triangularity, and squareness are all beneficial, as is high Zeff. When elongation is also allowed to vary, a ~65% increase in fusion power can be achieved. While not commonly considered, we find squareness is an important lever on fusion power. The plasma performance is limited by the Greenwald density limit constraint. This workflow developed here and demonstrated with the example of ARC V3A can readily be applied to other tokamak designs.
