Interaction of 1.3-μm laser radiation with thin foil targets

Comprehensive studies of the hydrodynamics and energy transport in laser-produced plasmas are presented. Thin low-Z foil targets (10^-5---10^-3 g/cm²) were irradiated with 300-ps pulses from the Asterix-III iodine laser (λ=1.3 {μ}m). Different diagnostics such as high-speed photography, plasma calorimetry, Ulbricht sphere for laser-light absorption measurements, and x-ray and ion techniques were used. Results on the velocity and energy of the accelerated foil, pressure, ablation rate, and lateral energy spread were obtained for a wide intensity range 10¹¹---10¹⁶ W/cm². Pressures exceeding 10 Mbar and foil velocities of up to 10⁸ cm/se observed. The experimental data are compared with one-dimensional hydrodynamic calculations using different values of electron heat-flux limitation. An indication of intensity-dependent flux inhibition was found: f≥0.1 at intensities below 10¹³ W/cm², but f=0.015-0.03 at intensities above 10¹⁴ W/cm².