基于多组分Navier-Stokes（N-S）方程组,开发了适用于CFD模拟软件Fluent的UDF源项程序,实现了在N-S方程中添加质量、动量、能量源项,在此基础上模拟了EUV光刻机收集镜腔室内锡等离子体的动态扩散过程,分析了背景氢气的压力（20 ~ 150 Pa）和流速（100 ~ 300 m/s）对锡等离子体空间分布的影响规律。结果表明,在单个激光脉冲周期内,锡等离子体的动能迅速以压缩波的形式传递给背景氢气,锡等离子体的扩散距离有限。在多脉冲条件下,锡等离子体会逐渐积累并在背景气体沿轴向的流动驱动下出现Kelvin-Helmholtz不稳定性。背景氢气的压力增加使得锡等离子体沿径向（垂直流动方向）的输运距离减小,对轴向输运距离影响不明显;背景氢气流速的增加使得锡等离子体径向输运距离减小,轴向输运距离增加;通过整合工况下的数据,本文建立了锡等离子体径向无量纲输运距离与雷诺数的定量关系式。
Based on the multi-component Navier-Stokes (N-S) equations, a User-Defined Function (UDF) source term program compatible with the CFD simulation software FLUENT was developed. This program facilitated the incorporation of mass, momentum, and energy source terms into the N-S equations. Building upon this foundation, the dynamic diffusion process of tin plasma within the collecting mirror chamber of an EUV lithography machine was simulated, and the impact of background hydrogen pressure (20~150 Pa) and flow rate (100~300 m/s) on the spatial distribution of tin plasma was analyzed. The results indicate that during a single laser pulse cycle, the kinetic energy of tin plasma is swiftly transferred to the background hydrogen in the form of a compression wave, resulting in a limited diffusion distance for the tin plasma. Under multi-pulse conditions, the tin plasma gradually accumulates, and Kelvin-Helmholtz instability emerges, driven by the axial flow of the background gas. An increase in background hydrogen pressure reduces the radial (perpendicular to the flow direction) transport distance of tin plasma, while exerting a negligible effect on the axial transport distance. Conversely, an increase in background hydrogen flow rate decreases the radial transport distance and increases the axial transport distance of tin plasma. By integrating data from various operating conditions, this study establishes a quantitative relationship between the radial dimensionless transport distance of tin plasma and the Reynolds number.
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