We report experimental and modeling results for the charge state distribution of laboratory photoionized neon plasmas in the first systematic study over nearly an order of magnitude range of ionization parameter $\xi \propto F/N_e$. The range of $\xi$ is achieved by flexibility in the experimental platform to adjust either the x-ray drive flux $F$ at the sample or the electron number density $N_e$ or both. Experimental measurements of photoionized plasma conditions over such a range of parameters enable a stringent test of atomic kinetics models used within codes that are applied to photoionized plasmas in the laboratory and astrophysics. From experimental transmission data, ion areal densities are extracted by spectroscopic analysis that is independent of atomic kinetics modeling. The measurements reveal the net result of the competition between photon-driven ionization and electron-driven recombination atomic processes as a function of $\xi$ as it affects the charge state distribution. Results from radiation-hydrodynamics modeling calculations with detailed inline atomic kinetics modeling are compared with the experimental results. There is good agreement in the mean charge and overall qualitative similarities in the trends observed with $\xi$ but significant quantitative differences in the fractional populations of individual ions.

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在 Z 处的实验室光电离等离子体实验中观察电离趋势

我们在近一个数量级的电离参数范围内的第一次系统研究中报告了实验室光电离氖等离子体电荷状态分布的实验和建模结果 $\xi \propto F/N_{\mathrm{电子}}$. 范围$\xi$ 通过实验平台的灵活性来调整 X 射线驱动通量 $F$ 在样品或电子数密度 $N_{\mathrm{电子}}$或两者。在这样一个参数范围内对光电离等离子体条件进行实验测量，可以对应用于实验室和天体物理学中的光电离等离子体的代码中使用的原子动力学模型进行严格的测试。从实验传输数据中，通过独立于原子动力学模型的光谱分析提取离子面密度。测量结果揭示了光子驱动电离和电子驱动复合原子过程之间竞争的最终结果$\xi$因为它会影响电荷态分布。将具有详细在线原子动力学模型的辐射流体动力学模型计算结果与实验结果进行比较。观察到的趋势的平均电荷和总体定性相似性有很好的一致性$\xi$ 但在单个离子的分数群体中存在显着的数量差异。