R矩阵不透明度计算：V. 氧离子O VI和O VII的光吸收截面与不透明度谱的温度-密度依赖性
R-matrix calculations for opacities: V. Temperature-density dependence of photoabsorption cross sections and opacity spectra of oxygen ions O VI and O VII
查看机构详情
- The Ohio State University（俄亥俄州立大学）
机构由 AI 辅助整理，请以论文原文为准。
浏览论文内容
中文总结 AI 辅助
本研究用R矩阵方法计算氧离子O VI和O VII的光吸收截面，揭示等离子体展宽随温度密度的变化，并发现与Opacity Project相比，新结果覆盖更高能量范围、含更丰富共振，对天体物理和ICF实验有重要意义。
中文摘要 AI 辅助
我们给出了类锂氧O VI和类氦氧O VII的R矩阵光吸收截面，并研究了在天体物理和实验室高能量密度（HED）等离子体源中，等离子体展宽如何随温度和密度变化而改变这些截面。所有原子系统都受到等离子体环境效应的影响，辐射的传播取决于通过束缚-束缚跃迁（作为谱线）和束缚-自由光电离截面中的自电离共振的光吸收。我们确定并展示了O VI和O VII中等离子体展宽开始的低温和高温-密度极限，证明了适用于广泛等离子体条件的通用特征和方法。计算沿着两条代表性的等温线进行，对应于太阳对流区底部（BCZ），温度为$T = 1 \ imes 10^6$和$2 \ imes 10^6$ K，电子密度$N_e = 10^{18}$-$10^{23}$ cm$^{-3}$。在每条等温线上，随着电子密度的增加，自电离共振逐渐溶解到连续谱中，在BCZ条件下，它们变平并合并到背景截面中，其密度远低于束缚-束缚线特征所需的密度。给出了包含里德伯共振系列（包括大的光激发核心（PEC）共振）的能量区域的示例。与之前的Opacity Project结果的比较表明：（i）R矩阵光电离截面覆盖了更高的能量范围，其中存在更丰富的自电离共振谱，这些共振未包含在OP中；（ii）相应的单色不透明度显示出显著的定量差异。这项工作普遍适用于天体物理学中HED等离子体的建模，以及惯性约束聚变（ICF）装置实验室实验中透射光谱的分析。
英文摘要
We present R-matrix photoabsorption cross sections for Li-like oxygen O VI and He-like oxygen O VII and examine how plasma broadening modifies them as a function of temperature and density in astrophysical and laboratory high-energy-density (HED) plasma sources. All atomic systems are subject to plasma environment effects, and the propagation of radiation depends on photoabsorption via bound-bound transitions as spectral lines and autoionizing resonances in bound-free photoionization cross sections. We identify and illustrate low and high temperature-density limits for the onset of plasma broadening in O VI and O VII, demonstrating general features and methodology applicable across a broad range of plasma conditions. Calculations are presented along two representative isotherms corresponding to the solar base of convection zone (BCZ) at $T = 1 \times 10^6$ and $2 \times 10^6$ K, and electron densities $N_e = 10^{18}$-$10^{23}$ cm$^{-3}$. Autoionizing resonances progressively dissolve into the continuum with increasing electron density at each isotherm, flattening and merging into the background cross sections at BCZ conditions, at much lower densities than bound-bound line features require. Illustrative examples are given for energy regions containing Rydberg resonance series, including large photoexcitation-of-core (PEC) resonances. Comparisons with previous Opacity Project results reveal that (i) the R-matrix photoionization cross sections cover a much higher energy range where a significantly richer spectrum of autoionizing resonances are present that are not included in OP, and (ii) the corresponding monochromatic opacities show significant quantitative differences. This work is generally applicable to modeling HED plasmas in astrophysics, and to the analysis of transmission spectra in laboratory experiments on inertial confinement fusion (ICF) devices.
