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

Abstract

Dense titanium plasma has been heated to an electron temperature up to 1300eV with a 100TW, high intensity short-pulse laser. The experiments were conducted using Ti foils (5μm thick) sandwiched between layers of either aluminum (1 or 2μm thick) or plastic (2μm thick) to prevent the effects of prepulse. Targets of two different sizes, i.e., 250×250μm2 and 1×1mm2 were used. Spectral measurements of the Ti inner-shell emission, in the region between 4and5keV, 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=1300eV of solid titanium plasma in ∼0.2μm thin layer. Higher bulk temperature (Te,bulk=100eV) for aluminum tamped compared to CH tamped targets (Te,bulk=40eV) 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.