Opacity Measurements of a Hot Iron Plasma Using an X-Ray Laser

The temporal evolution of the opacity of an iron plasma at high temperature (30–350 eV) and high density (0.001–0.2 g cm-3) has been measured using a nickel-like silver x-ray laser at 13.9 nm. The hot dense iron plasma was created in a thin (50 nm) iron layer buried 80 nm below the surface in a plastic target that was heated using a separate 80 ps pulse of 6–9 J, focused to a 100 µm diameter spot. The experimental opacities are compared with opacities evaluated from plasma conditions predicted using a fluid and atomic physics code.