The recent development of compact, short (ps or sub-ps) X-ray sources gives access to the structural nature of short time-scale phenomena and to the study of very transient systems such as warm dense materials. Among the structural tools used for the study of static (solid) materials,X-ray Absorption Fine Structure (XAFS) spectroscopy has proven to provide useful information on the local structure (atomic arrangement) and on the electronic Density of States. In a context where the matter is disordered but highly correlated, we present K-edge absorption studies of warm, dense aluminum. The range of temperature starts from the solid and extend to the strongly correlated plasma regime. We describe here two theoretical approaches for the the calculation of the K-edge absorption features. The first one involves a (Modified) HyperNetted Chain - Neutral Pseudo Atom (MHNC-NPA) model of dense matter coupled with a specific model of the XAFS features. The second one is based on ab initio Quantum Molecular Dynamics (QMD) simulations from which a Kubo-Greenwood formulation combined with the Projector Augmented Wave (PAW) formalism gives a direct access to the X-ray absorption spectra. These spectra are compared with recent Kedge absorption measurements in aluminum targets isochorically heated by laser-created protons and probed by a short X-ray backlighting source.
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