Creation of hot dense matter in short-pulse laser-plasma interaction with tamped titanium foils

Dense titanium plasma has been heated to an electron temperature up to 1300 eV with a 100 TW, high intensity short-pulse laser. The experiments were conducted using Ti foils (5 μm thick) sandwiched between layers of either aluminum (1 or 2 μm thick) or plastic (2 μm thick) to prevent the effects of prepulse. Targets of two different sizes, i.e., 250x250 μm2 and 1x1 mm2 were used. Spectral measurements of the Ti inner-shell emission, in the region between 4 and 5 keV, were taken from the front-side (i.e., the laser illuminated side) of the target. The data show large shifts in the Kα emission from open-shell ions, suggesting bulk heating of the sample at near solid density, which was largest for reduced mass targets. Comparison with collisional radiative and 2D radiation hydrodynamics codes indicates a peak temperature of Te,peak=1300 eV of solid titanium plasma in ∼0.2 μm thin layer. Higher bulk temperature (Te,bulk=100 eV) for aluminum tamped compared to CH tamped targets (Te,bulk=40 eV) was observed. A possible explanation for this difference is described whereby scattering due to the nuclear charge of the tamping material leads to modified electron transport behavior