Laser-produced plasma-wall interaction probed by X-ray spectroscopy

Jets of laser-generated plasma represent a flexible and well-defined model environment for investigation of plasma interactions with solid surfaces (walls). The pilot experiments carried out on the iodine laser system (5-200 J, 0.44 micron, 0.25-0.3 ns, <10¹⁶ W/cm²) at the PALS Research Centre in Prague are reported. Modification of macroscopic characteristics of the Al plasma jets produced at laser-irradiated double-foil Al/Mg targets is studied by high-resolution, high-dispersion X-ray spectroscopy. The spatially variable, complex satellite structure observed in emission spectra of the Al Ly alpha group proves a formation of rather cold dense plasma at the laser-exploded Al foil, an occurrence of the hot plasma between both foils and subsequent thermalization, deceleration and trapping of Al ions in the colliding plasma close to the Mg foil surface. The spectra interpretation based on the collisional-radiative code is complemented by 1D and 2D hydrodynamic modeling of the plasma expansion and interaction of counter-propagating Al/Mg plasmas. The obtained results demonstrate a potential of high resolution X-ray diagnostics in investigation of the laser-produced plasma-wall interactions.

O. Renner, R. Liška, F. B. Rosmej: Laser-produced plasma-wall interaction, Laser Part. Beams 27, 725 (2009).