KrF laser-plasma interaction experiments with ns and ps pulses

Abstract

We report on KrF laser-plasma interaction studies at focused intensities up to 4 × 1014 W/cm2 for pulse durations of 1–2 ns and up to 1015 W/cm2 for pulse duration of 100 ps. The longer-pulse experiments are concerned with quantifying two important features of the ablating plasma. Stimulated Brillouin scattering at moderately large L/λ has been measured in detail as a function of intensity, target Z, and angle of incidence θ to compare with modeling calculations of backscatter in inhomogeneous plasma. In addition, electrodynamic charge analyzer measurements have been made for varying intensity and target Z to compare with hydrodynamic calculations of ion expansion and recombination. In the short-pulse experiments, we report on X-ray conversion measurements for 100-ps laser-irradiated targets of varying Z at laser intensities of 1·5 × 1014 and 1015 W/cm2. In particular, it is shown that higher laser intensity leads to a substantial increase in X-ray conversion efficiency.