The space-filter approach has proved a fundamental tool in studying turbulence in neutral fluids, providing the ability to analyze scale-to-scale energy transfer in configuration space. It is well known that turbulence in plasma presents challenges different from neutral fluids, especially when the scale of interests include kinetic effects. The space-filter approach is still largely unexplored for kinetic plasma. Here we derive the space-filtered (or, equivalently "coarse-grained") equations in configuration space for a quasi-neutral hybrid-kinetic plasma model, in which ions are fully kinetic and electrons are a neutralizing fluid. Different models and closures for the electron fluid are considered, including finite electron-inertia effects and full electrons' pressure-tensor dynamics. Implications for the cascade of turbulent fluctuations in real space depending on different approximations are discussed.

中文翻译：

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准中性混合动力学模型的空间滤波技术

空间滤波器方法已被证明是研究中性流体湍流的基本工具，提供了分析配置空间中尺度到尺度能量传递的能力。众所周知，等离子体中的湍流带来了不同于中性流体的挑战，尤其是当关注的范围包括动力学效应时。对于动力学等离子体，空间过滤器方法在很大程度上仍未被探索。在这里，我们为准中性混合动力等离子体模型在配置空间中推导出空间过滤（或等效“粗粒度”）方程，其中离子是完全动力学的，而电子是中和流体。考虑了电子流体的不同模型和闭包，包括有限电子惯性效应和全电子压力张量动力学。