Laboratory astroparticle physics

Abstract:

Abstract. Results of a recent experiment to measure laser ablation rates from solid targets consisting of thin (50 nm) Fe at irradiances of ~ 2×1013 Wcm−2 are presented. A Ni-like Ag X-ray laser at 13.9 nm was utilised to probe the targets and measurements of the transmission of the X-ray laser through the target were recorded by a flat-field spectrometer. The laser ablation rate is determined by the transmission of the X-ray laser through the remaining, unablated, iron layer. A self-regulating model of laser ablation is fitted to the experimental data to give a value of the absorption, A, of the heating laser in the target plasma of A = 0.01.

Abstract:

We report the creation of solid-density aluminum plasma using free-electron laser (FEL) radiation at 13.5 nm wavelength. Ultrashort pulses were focused on a bulk Al target, yielding an intensity of 2× 1014/cm2. The radiation emitted from the plasma was measured using an xuv spectrometer. Bremsstrahlung and line intensity ratios yield consistent electron temperatures of about 38 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. © 2008 The American Physical Society.