Smoothing of ablation pressure nonuniformities in the laser-plasma corona during heating of laser fusion targets

A method for smoothing ablation pressure nonuniformities during heating of laser fusion targets is described which utilises an extra laser pulse preceding the main pulse. Theoretical and experimental data are presented on heating of thin (3–10 μm) foils (simulating the target shell) by a spatially nonuniform laser beam. In the experiments, the laser pulse width at half maximum was 2 ns and the pulse energy was 2–30 J, which ensured a power density on the target surface from 1013 to 1014 W cm-2. The experimental data are analysed using two-dimensional numerical simulations. The experimental and simulation results demonstrate that this approach is sufficiently effective. The optimal laser prepulse parameters are determined.