Isochoric Heating of Solid Aluminum by Ultrashort Laser Pulses Focused on a Tamped Target

Abstract

We have studied the $K$-shell emission of an Al plasma which was generated by focusing a high contrast 150 fs laser pulse at a wavelength of 395 nm and intensity of $5\ifmmode\times\else\texttimes\fi{}{10}^{17}\mathrm{W}/{\mathrm{cm}}^{2}$ on a flat Al target tamped by a thin surface layer of MgO. The measured resonance lines ( ${\mathrm{Ly}}_{\ensuremath{\alpha}}$, ${\mathrm{He}}_{\ensuremath{\alpha}}$, and ${\mathrm{He}}_{\ensuremath{\beta}}$) and their Li-like and He-like satellites are extremely broadened and show a red polarization shift. Analysis of the ${\mathrm{Ly}}_{\ensuremath{\alpha}}$ and ${\mathrm{He}}_{\ensuremath{\beta}}$ satellites yields an electron temperature of $\ensuremath{\approx}300\mathrm{eV}$ and an electron density of $(5--10)\ifmmode\times\else\texttimes\fi{}{10}^{23}{\mathrm{cm}}^{\ensuremath{-}3}$.