发表机构
University of Washington; New Jersey Institute of Technology; Princeton University（华盛顿大学; 新泽西理工学院; 普林斯顿大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究在连续动力学框架中实现能量依赖的粒子诱导电子发射模型，揭示其对聚变鞘层输运性质的影响，发现鞘层从经典到空间电荷限制的转变主要由电子诱导发射决定，且PIEE增加壁面热和粒子负载的机制为预鞘层中的碰撞能量传递。
AI 中文摘要
在连续动力学框架中，严格实现了与能量相关的离子和电子诱导电子发射，以揭示其对施加偏置电位壁的鞘层中等离子体性质标度的影响。该方法提出了一种建模粒子诱导电子发射（PIEE）的新方法，包括：1）改进的产额和能谱拟合函数；2）使用SRIM以及Lindhard公式和修正Bethe公式的求和来获得精确的阻止本领；3）基于密度泛函理论（DFT）计算对PIEE能谱和离子诱导产额进行结合能修正。发射模型作为完全能量依赖的动态边界条件实现。本研究针对钨和石墨壁，因其在磁聚变实验中的相关性。从流体理论推导出方程，预测离子和电子诱导发射对鞘层结构的相对重要性。模拟为理论预测提供了证据，表明从经典鞘层到空间电荷限制（SCL）鞘层的转变主要取决于电子诱导发射。此外，先前文献中关于电子发射导致壁面热和粒子负载增加的论断得到支持，但观察到增加的机制不同。由PIEE引起的热通量和粒子通量增加主要由预鞘层中发射电子的碰撞能量传递驱动。最后，本研究所建模装置的定量预测与先前的建模工作和实验测量结果一致。
英文摘要
A rigorous implementation of energy-dependent ion- and electron-induced electron emission in a continuum-kinetic framework is used to reveal their effects on the scaling of plasma properties in the sheath with an applied bias potential to the walls. The approach comes with a novel methodology for modeling particle-induced electron emission (PIEE) that includes 1) improved fitting functions for the yield and spectra, 2) the use of SRIM and a summation of the Lindhard formula and a modified Bethe formula for obtaining accurate stopping powers, and 3) a binding energy correction to the PIEE spectra and ion-induced yield based on density functional theory (DFT) calculations. The emission models are implemented as a fully energy dependent and dynamic boundary condition. For this investigation, tungsten and graphite walls are studied for their relevance in magnetic fusion experiments. Equations are derived from fluid theory that predict the relative importance of ion- and electron-induced emission on the structure of the sheath. The simulations provide evidence for the theoretical predictions, showing that a transition from a classical to space-charge limited (SCL) sheath depends primarily on electron-induced emission. Furthermore, claims in previous literature of increased heat and particle loads to the walls due to electron emission are supported, however differing mechanisms for the increase are observed. The increased thermal and particle fluxes due to PIEE are primarily driven by collisional transfer of energy from emitted electrons in the presheath. Finally, quantitative predictions for the device modeled in this study coincide with previous modeling efforts and experimental measurements.
