Spatially and temporally resolved visible absorption spectroscopy is performed on sodium D-lines present as surface contaminants on an expanded dense aluminum plasma plume. An 80-ns FWHM, intense, relativistic electron beam deposits 5.4 J into a 100-μm-thick Al foil, which isochorically heats and subsequently hydrodynamically expands the material through the warm dense matter state and into a classical-like plasma state, with a coupling parameter of approximately 0.2 and a degeneracy parameter of approximately 270. The Na contamination, carried along with the expanding plume, shows saturated absorption features in the dense Al continuum for $\lambda >$ 450 nm. X-ray photoelectron spectroscopy and laser-induced breakdown spectroscopy confirm Na is a surface contaminant with an atomic concentration of $\sim 0.1\%$ when interrogating identical foil samples. A spectroscopic-quality radiation transport model is used to post-process 2D hydrodynamic simulations to interpret the plasma conditions based on the measured Na 3p-3s doublet line profiles. A sodium number density of $3\times {10}^{15}$ cm⁻³ best matches the experimental spectra, which originate from a dense surface plasma with $n_e=3.0\pm 0.8\times {10}^{18}$ cm⁻³.

中文翻译：

---

电子束等速加热的膨胀致密铝等离子体的钠示踪测量

在空间上和时间上分辨的可见吸收光谱是对钠D线进行的，该钠D线作为表面污染物存在于膨胀的致密铝等离子体羽上。一个80-NS FWHM，激烈，相对论电子束沉积5.4Ĵ成100- μ微米厚的Al箔，其isochorically加热，并且随后流体动力学通过暖致密物质状态并进入古典状等离子体状态扩展材料，具有耦合参数大约为0.2，简并参数大约为270。Na污染与膨胀的羽状流一起，在致密的Al连续谱中显示出饱和的吸收特征。$\lambda >$ 450 nm。X射线光电子能谱和激光诱导击穿能谱证实，Na是一种表面污染物，原子浓度为$〜0.1％$当询问相同的箔样品时。使用光谱质量的辐射传输模型对2D流体动力学模拟进行后处理，以基于测得的Na 3p-3s双峰线轮廓解释等离子体条件。钠数密度为$3\times {10}^{15}$cm ^-3与实验光谱最匹配，该光谱来自密集的表面等离子体${ñ}_{Ë}=3.0\pm 0.8\times {10}^{\mathrm{18岁}}$厘米^-3。