Model calculations of extreme ultraviolet gain from laser-irradiated aluminium foils

Earlier studies of extreme ultraviolet gain from the transition between the n=2 and n=3 states of hydrogen-like carbon are extended to hydrogen-like aluminium ions. An experiment where a thin aluminium foil is irradiated by a high-power laser in a line focus is simulated with a similarity or self-similar plasma expansion code containing laser heating, ionisation and recombination, and radiation transport algorithms. The target and laser parameters which, according to the code, optimise the n=3 to 2 transition (Balmer alpha ) gain for Al XIII are determined. The irradiation of an aluminium foil of thickness 0.5 mu m in a line focus of width 40 mu m with a neodymium laser of energy 50 J cm -1 and pulse duration 20 ps is predicted to produce Al XIII Balmer alpha 38.7 AA) small signal gain of approximately 15 cm -1 along the focal line. The validity of the similarity model for the experiment envisaged is examined using a two-dimensional hydrodynamic code to simulate the early laser-irradiated foil expansion.