Energy Transport through High-ZMetal Foil in a Laser-Produced Plasma

Double-layer thin films of high-$Z$ metal and low-$Z$ polyethylene and each single-layer film were irradiated with a 1.06-μm, 200-psec laser pulse at intensities from ${10}^{14}$ to 7 × ${10}^{14}$ ${\mathrm{W}/\mathrm{c}\mathrm{m}}^2$. From the measurements of the transmittance of the laser through these films, the spatial distributions of the transmitted light, expanding ion currents, and x rays, the energy transport is found to be due not only to superthermal electrons but also to x-ray radiation in a high-$Z$ material.