Recently, it was shown that strong electron thermionic emission from material walls could result in the formation of an “inverse sheath,” which prevents the flow of cold ions to the wall.^[1–3] Such regimes look very favourably from the point of view of plasma–material interactions at the edge of magnetic fusion devices, where the problem of the erosion of plasma‐facing components under ion irradiation is one of the key issues for the development of future magnetic fusion reactors. However, it is not clear whether such regimes are compatible with edge plasma parameters and heat removal requirements in fusion reactors. To address the issue of practicality of the “inverse sheath” regime for edge tokamak plasma conditions, we perform a set of numerical simulations with 2D edge plasma transport code UEDGE^[4] for a DIII‐D‐like geometry and magnetic configuration. To describe both “standard” and “inverse sheath” conditions within the framework of the UEDGE code (which does not consider the sheath region per se), at the material surfaces, we apply effective boundary conditions that emulate both “standard” and “inverse sheath” regimes. We demonstrate that, for the same input parameters, spatial distributions of edge plasma parameters corresponding to detached divertor and “inverse sheath” regimes are similar, with only a few minor differences. We discuss the compatibility of “inverse sheath” regimes with core plasma parameters.

中文翻译：

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托卡马克边缘等离子体模拟中反鞘对偏滤器等离子体性能的影响

最近，研究表明，从材料壁发出的强烈的电子热电子可能导致“逆鞘”的形成，从而阻止冷离子流向壁。^[1–3]从磁聚变设备边缘的等离子体与材料相互作用的角度来看，这样的机制非常有利，在该领域，离子辐照下面向等离子体的组件的腐蚀问题是解决该问题的关键问题之一。发展未来的磁聚变反应堆。然而，尚不清楚这些方案是否与聚变反应堆中的边缘等离子体参数和除热要求兼容。为了解决边缘托卡马克等离子体条件下的“逆鞘”机制的实用性问题，我们使用二维边缘等离子体传输代码UEDGE执行了一组数值模拟^[4]用于DIII-D类几何形状和磁性配置。为了在UEDGE代码的框架中描述“标准”和“反向鞘”条件（其本身不考虑鞘区域），在材料表面，我们应用了有效的边界条件来模拟“标准”和“反向鞘”鞘”政权。我们证明，对于相同的输入参数，对应于分离的偏滤器和“逆鞘”状态的边缘等离子体参数的空间分布是相似的，只有一些小差异。我们讨论了“逆鞘”机制与核心血浆参数的相容性。