Wendelstein 7-X 中准稳态等离子体性能的弹丸尺寸标度

中文摘要 AI 辅助

在 Wendelstein 7-X (W7-X) 中，使用连续低温弹丸注入器实现了长脉冲高性能等离子体。氢冰弹丸将粒子直接沉积在约束区域内。如果粒子沉积在等离子体内部足够深的位置，它们会产生密度梯度，抑制离子温度梯度湍流并改善等离子体约束。然而，在注入多个弹丸且等离子体密度和温度升高后，等离子体性能开始饱和。在本工作中，我们分析了 2024 年和 2025 年进行的多次弹丸注入实验，期间注入的弹丸尺寸无意中发生了变化。该分析揭示了弹丸尺寸与 W7-X 等离子体准稳态储能之间的正相关性。尽管这种弹丸尺寸依赖性可以从弹丸烧蚀物理学中得到定性理解，但测得的沉积位置与中性气体屏蔽 (NGS) 模型预测存在定量差异。这种差异表明弹丸云存在显著的向内输运。这里发现的趋势表明，注入更大的弹丸可以进一步提高等离子体性能。

英文摘要

A continuous cryogenic-pellet injector has been used to realize long-pulse high-performance plasmas in Wendelstein 7-X (W7-X). A hydrogen ice pellet deposits particles directly in the confined region. If the particles are deposited sufficiently far inside the plasma, they produce a density gradient that suppresses ion-temperature-gradient turbulence and improves plasma confinement. However, after multiple pellets have been injected and the plasma density and temperature have increased, the plasma performance begins to saturate. In this work, we analyze multiple pellet-injection experiments conducted in 2024 and 2025, during which the injected pellet sizes varied unintentionally. This analysis reveals a positive correlation between pellet size and the quasi-steady-state stored energy of W7-X plasmas. Although this pellet-size dependence can be understood qualitatively from pellet-ablation physics, the measured deposition position differs quantitatively from the neutral-gas-shielding (NGS) model prediction. This discrepancy suggests significant inward transport of the pellet cloud. The trend identified here suggests that injection of even larger pellets could further improve plasma performance.

发表机构

• Oak Ridge National Laboratory（橡树岭国家实验室）
• Max Planck Institute for Plasma Physics（马克斯·普朗克等离子体物理研究所）
• Type One Energy

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