LASER PLASMA ENERGY ANGULAR DISTRIBUTION AND ABSORPTION SCALING LAWS

Experiments to study the laser plasma angular distribution and the absorption scaling laws for planar targets are reported. Gaussian (0.3 to 2.2ns) 1.06μm laser pulse with energy from 2 to 50J at average laser intensity of 1.8×10¹³ to 1.1 × 10¹⁵W/cm², were used to irradiate thick, Au, Ag, Ti, Al, and C₈H₈ targets. The absorption was measured with plasma calorimeters. The experimental data were fitted with exponential functions. Scaling relations of the absorption efficiencies as function of laser intensity, pulse duration, and target material atomic number were presented, respectively. The scaling relations of absorption efficiency are qualitatively consistent with theoretical relations of the inverse- bremsstrahlung absorption.