A new hybrid fluid-kinetic approach for the hydrogenic neutrals (atoms and molecules) in the plasma edge is presented. The hybrid approach combines a fully kinetic model for the atoms in the low-collisional regions near the vessel wall, and for the molecules in the whole plasma edge domain, with a micro–macro approach for atoms originating from recycling at the divertor targets, volumetric recombination, and dissociation of molecules. With the micro–macro approach, the originally scattering-dominated collision term due to charge-exchange collisions in the kinetic equation is transformed to an absorption-dominated term, while a large part of the neutral population is treated through a fluid approach. For JET L-mode plasmas, the premature termination of Monte Carlo particle trajectories in the hybrid approach leads to a reduction of the CPU time by approximately a factor 3 for a high-recycling case and by approximately a factor 11 for a partially detached case compared with a simulation with fully kinetic neutrals and the same amount of particles. For coupled fluid plasma – hybrid neutral simulations – the hybrid approach predicts the plasma divertor target profiles with a maximum hybrid-kinetic discrepancy of approximately 30%.

中文翻译：

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氢等离子体边缘中性粒子的微观-宏观和空间混合流体动力学方法的结合

提出了一种新的混合流体动力学方法，用于等离子体边缘中的氢中性体（原子和分子）。混合方法结合了容器壁附近低碰撞区域中的原子和整个等离子体边缘域中的分子的完全动力学模型，以及源自偏滤器目标回收的原子的微观-宏观方法，体积分子的重组和解离。使用微观-宏观方法，将动力学方程中由于电荷交换碰撞导致的最初以散射为主的碰撞项转换为以吸收为主的项，而大部分中性粒子通过流体方法处理。对于 JET L 型等离子体，与具有完全动力学中性的模拟相比，混合方法中蒙特卡罗粒子轨迹的过早终止导致 CPU 时间在高回收情况下减少了大约 3 倍，在部分分离的情况下减少了大约 11 倍和相同数量的粒子。对于耦合流体等离子体 - 混合中性模拟 - 混合方法预测等离子体偏滤器目标分布，最大混合动力学差异约为 30%。