A recent study (2020 Nat. Commun. 11 2334) has found that transitions between multiply-excited configurations in open 4d-subshell tin ions are the dominant contributors to intense EUV emission from dense, Nd:YAG-driven (laser wavelength λ = 1.064μm) tin plasmas. In the present study, we employ the Los Alamos Atomic code to investigate the spectral contribution from these transitions under industrially-relevant, CO₂ laser-driven (λ = 10.6μm) tin plasma conditions. First, we employ Busquet’s ionisation temperature method to match the average charge state ⟨Z⟩ of a non-local-thermodynamic equilibrium (non-LTE) plasma with an LTE one. This is done by varying the temperature of the LTE calculations until a so-called ionisation temperature T _Z is established. Importantly, this approach generates LTE-computed configuration populations in excellent agreement with the non-LTE populations. A corollary of this observation is that the non-LTE populations are well-described by Boltzmann-type exponential distributions having effective temperatures T _eff ≈ T _Z . In the second part of this work, we perform extensive level-resolved LTE opacity calculations at T _Z . It is found that 66% of the opacity in the industrially-relevant 2% bandwidth centred at 13.5nm arises from transitions between multiply-excited states. These results reinforce the need for the consideration of complex, multiply-excited states in modelling the radiative properties of laser-driven plasma sources of EUV light.

最近的一项研究（。2020纳特COMMUN 11 2334）已发现，在打开4乘法激构型之间转变d -subshel​​l锡离子是主要贡献者从致密强烈EUV发射，钕：YAG驱动（激光波长λ = 1.064 μ M）锡等离子体。在本研究中，我们采用了洛斯阿拉莫斯原子代码来调查从这些过渡工业相关，CO下的光谱贡献₂激光驱动（λ = 10.6 μ M）锡等离子体条件。首先，我们采用Busquet的电离温度的方法来匹配平均蓄⟨ ž1/3的非局部热力学平衡（non-LTE）等离子体与LTE之一。这是通过改变LTE计算的温度直到建立所谓的电离温度T _Z来完成的。重要的是，此方法生成的LTE计算配置种群与非LTE种群非常吻合。这种观察的必然结果是在非LTE人群由具有有效温度波尔兹曼型指数分布充分描述Ť _EFF ≈ Ť _ž。在这项工作的第二部分中，我们在T _Z上执行了广泛的级别解析的LTE不透明度计算 。发现在与工业相关的2％带宽（以13.5nm为中心）中，不透明性的66％来自多重激发态之间的跃迁。这些结果加强了在对EUV光的激光驱动等离子体源的辐射特性进行建模时需要考虑复杂的多激发态的需要。