Line emission radiation during early-time interaction of an intense short laser pulse with an ultrathin planar aluminum target

The interaction of an intense short laser pulse with an ultrathin planar aluminum foil is investigated with a fully relativistic particle-in-cell model self-consistently coupled to an atomic dynamics model describing the non-local thermodynamic equilibrium level population dynamics and radiative behavior of a plasma evolving on a picosecond timescale. For typical experimental conditions, laser pulses with energy 1 J, intensity 10²⁰ W cm⁻², and duration 40 fs, a synthetic spectrum for the emission lines is generated as a function of time for lines emanating in the hydrogen- and helium-like ionization stages. It is found that He_α, He_β, Ly_α, and Ly_β lines have intensities above the Bremsstrahlung continuum and could serve as diagnostics for the evolving plasma condition. (paper)