Demonstrating electromagnetic control of free-surface, liquid-metal flows relevant to fusion reactors

Plasma-facing components (PFC's) made from solid materials may not be able to withstand the large heat and particle fluxes that will be produced within next-generation fusion reactors. To address the shortcomings of solid PFC's, a variety of liquid-metal (LM) PFC concepts have been proposed. Many of the suggested LM-PFC designs rely on electromagnetic restraint (Lorentz force) to keep free-surface, liquid-metal flows adhered to the interior surfaces of a fusion reactor. However, there is very little, if any, experimental data demonstrating that free-surface, LM-PFC's can actually be electromagnetically controlled. Therefore, in this study, electrical currents were injected into a free-surface liquid-metal that was flowing through a uniform magnetic field. The resultant Lorentz force generated within the liquid-metal affected the velocity and depth of the flow in a controllable manner that closely matched theoretical predictions. These results show the promise of electromagnetic control for LM-PFC's and suggest that electromagnetic control could be further developed to adjust liquid-metal nozzle output, prevent splashing within a tokamak, and alter heat transfer properties for a wide-range of liquid-metal systems.

采用固体材料制造的面向等离子体部件（Plasma-facing components, PFCs），或许难以承受下一代聚变反应堆内将产生的高热流与粒子流。为解决固体PFCs的上述缺陷，学界已提出多种液态金属（liquid-metal, LM）PFC设计方案。多数已提出的LM-PFC设计方案均依靠电磁约束（洛伦兹力，Lorentz force），使带有自由表面的液态金属流能够附着在聚变反应堆的内壁表面。然而，目前几乎尚无实验数据能够证明，自由表面型LM-PFCs可通过电磁方式实现有效控制。因此，本研究将电流注入至流经均匀磁场的自由表面液态金属中。液态金属内部产生的洛伦兹力以可控方式调控了流体的流速与流深，且与理论预测结果高度吻合。上述研究结果证实了电磁控制用于LM-PFCs的应用前景，并表明可进一步开发电磁控制技术，以调节液态金属喷嘴的输出量、防止托卡马克（tokamak）内出现溅射，并针对各类液态金属系统调整其传热特性。