We report the creation of solid-density aluminum plasma using free-electron laser (FEL) radiation at $13.5\mathrm{nm}$ wavelength. Ultrashort pulses were focused on a bulk Al target, yielding an intensity of $2\times {10}^{14}\mathrm{W}∕{\mathrm{cm}}^2$. The radiation emitted from the plasma was measured using an xuv spectrometer. Bremsstrahlung and line intensity ratios yield consistent electron temperatures of about $38\mathrm{eV}$, supported by radiation hydrodynamics simulations. This shows that xuv FELs heat up plasmas volumetrically and homogeneously at warm-dense-matter conditions, which are accurately characterized by xuv spectroscopy.

• Received 25 April 2008

DOI:https://doi.org/10.1103/PhysRevE.78.066406