Laser interaction with low-density carbon foam

Experiments were performed with a 15 J/500 ps Nd:glass laser (λ = 1064 nm) focussed to an intensity >10¹⁴ W/cm². X-ray emissions from carbon foam and 5% Pt-doped carbon foam of density 150-300 mg/cc were compared with that of the solid carbon targets. The thickness of the carbon foam was 15 μm on a graphite substrate. X-ray emission was measured using semiconductor X-ray diodes covered with various fil- ters having transmissions in different X-ray spectral ranges. It covered X-ray spectrum of 0.8=8.5 keV range. The X-ray emission in the soft X-ray region was observed to in- crease to about 1.8 times and 2.3 times in carbon foam and Pt-doped foam, respectively with respect to solid carbon. In hard X-rays, there was no measurable difference amongst the carbon foam, Pt-doped carbon foam and solid carbon. Scanning electron microscope (SEM) analysis demonstrates that foam targets smoothens the crater formed by the laser irradiation.