Demonstration of gold foam plasma as bright x-ray source and slow ion emitters

In this paper, enhancement in x-ray emission and reduction of kinetic energy of ions from low density foam plasma is demonstrated by performing experiment and hydrodynamic simulation. The plasma is produced by irradiation of solid gold and gold foam targets (densities 0.2 g/cc, 0.13 g/cc and 0.1 g/cc) at intensities in the range of 4 × 1013–1 × 1014 W cm−2. Time resolved x-ray emission is measured by an x-ray streak camera with 10 ps resolution. The x-ray flux measured by the streak camera from low density gold foam shows a 13% enhancement in comparison to solid gold in the spectral range >0.8 keV and above. Decrease in velocity of ions is observed in low density gold foam. In solid gold, thermal ions peak velocity is 31 × 104 m s−1 and spread in narrow energy width, however, in case of 0.1 g/cc, peak velocity reduces to 6 × 104 m s−1 towards target normal and emitted in broad energy range. Shadowgraphy results also provide evidence of narrower expansion of plasma from solid gold. However, total ion flux from low density gold foam is comparable to ion flux of solid gold indicating the process of volumetric absorption.