Atomic processes in plasmas created by an ultra-short laser pulse

Point projection K-shell absorption spectroscopy has been used to measure absorption spectra of transient aluminum plasma created by an ultra-short laser pulse. 1s-2p and 1s-3p absorption lines of weakly ionized aluminum were measured for an extended range of densities in a relatively low-temperature regime. Independent plasma characterization was obtained from frequency domain interferometry (FDI) diagnostic and allows the interpretation of the absorption spectra in terms of spectral opacities. The experimental spectra are compared with opacity calculations using the density and temperature inferred from the analysis of the FDI data.