Production of hot near-solid-density plasma by electron energy transport in a laser-produced plasma

Targets with a layer of aluminum buried beneath a plastic overlay have been irradiated with 0.53 μm wavelength, 20-ps pulse length light at (1–2)×${10}^{16}$ W ${\mathrm{cm}}^{\mathrm{-}2}$. The widths of Stark broadened Al x i i 1$s^{21}$ $S_0$–1s3p ${}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ spectral lines and the ratios of satellite line intensities to the Al x i i 1$s^2$m ${}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$–1s2p ${}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ spectral line emitted from the aluminum layer imply electron densities up to (6–8)×${10}^{22}$ ${\mathrm{cm}}^{\mathrm{-}3}$. This result is a direct observation of significant energy transport to densities close to solid.