Mayes D C, Mancini R C, Lockard T E, Hall I M, Bailey J E, Loisel G P, Nagayama T, Rochau G A, Liedahl D A
Department of Physics, University of Nevada, Reno, Nevada 89557, USA.
Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
Phys Rev E. 2021 Sep;104(3-2):035202. doi: 10.1103/PhysRevE.104.035202.
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 ξ∝F/N_{e}. The range of ξ 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 ξ 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 ξ but significant quantitative differences in the fractional populations of individual ions.
我们报告了在近一个数量级的电离参数ξ∝F/Nₑ范围内首次进行系统研究时，实验室光致电离氖等离子体电荷态分布的实验和建模结果。通过实验平台的灵活性来调节样品处的X射线驱动通量F、电子数密度Nₑ或两者，从而实现了ξ的范围。在此参数范围内对光致电离等离子体条件进行实验测量，能够对应用于实验室和天体物理学中光致电离等离子体的代码内所使用的原子动力学模型进行严格测试。从实验透射数据中，通过与原子动力学建模无关的光谱分析提取离子面密度。这些测量揭示了光子驱动的电离与电子驱动的复合原子过程之间竞争的净结果，它是作为ξ的函数，因为ξ会影响电荷态分布。将具有详细内联原子动力学建模的辐射流体动力学建模计算结果与实验结果进行了比较。在平均电荷方面有良好的一致性，并且在观察到的随ξ变化的趋势上有总体定性相似性，但在各个离子的分数丰度上存在显著的定量差异。
