Momentum measurements of laser produced plasma

The momentum transfer, the angular distribution of the blow-off plasma and cratering effects caused by the impact on an Al slab target of focused high power Nd:glass laser light with power densities in the range of 2*10 12 -4*10 13 W cm -2 were studied. Momentum measurements were performed using a physical ballistic pendulum, capable of measuring momenta as small as 3*10 -3 dyn s. The target recoil momentum was found to depend on the 3/4 power of the laser energy, in good agreement with theoretical calculations. In the range of intensities of these experiments, no indication of nonlinear forces in the plasma was found. The observed crater diameter was found to depend on the fourth root of the laser energy and its size indicated that it was a result of the action of the laser-induced shock wave.