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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 λ> 450 nm. X-ray photoelectron spectroscopy and laser-induced breakdown spectroscopy confirm Na is a surface contaminant with an atomic concentration of ∼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 3×1015 cm−3 best matches the experimental spectra, which originate from a dense surface plasma with ne=3.0±0.8×1018 cm−3.

A spatially resolved air-wedge shearing interferometer and shadowgraph diagnostic provides measurements of electron density with a resolution of [Formula: see text]40 [Formula: see text]m. A [Formula: see text]100-ns-long, monoenergetic electron bunch at 19.8 MeV and a current of 1.4 kA ([Formula: see text] [Formula: see text]) heats 100-[Formula: see text]m-thick aluminum (Al) foils in a 1-mm-spot to [Formula: see text] eV. A 5-ns-long, [Formula: see text]60 mJ, frequency doubled Nd:YAG laser probes the dense Al plasma. Electron densities up to [Formula: see text] are resolved; the maximum resolvable density is limited by opacity, transmission, and spatial fringe density achievable with the detector. This diagnostic provides measurements of the total phase shift, transmission, and electron density. Several measurements at different time slices provide the ability to determine the velocity of the leading edge of the shadowgraph and compare it to the motion of different density shells. These measurements are also compared to radiation hydrodynamics simulations. A rough quantitative agreement is shown between the hydro simulations and the measurements; there are differences in the exact density distributions.