Correlation of stress-wave profiles and the dynamics of the plasma produced by laser irradiation of plane solid targets

The interaction of 20-nsec 300-MW pulses of 1.06-μm laser radiation with thick aluminum targets in vacuum has been studied. The time history of the target impulse has been measured with a Sandia quartz gauge. A time sequence of plasma density maps constructed from floating double-probe data has been used with measured expansion velocities to estimate the plasma momentum. The results show that the stress wave is predominantly produced by about 10% of the evaporated target material which is ionized and expands from the surface in the form of a hot plasma during and shortly after the laser pulse. The estimated momentum of the plasma and neutral emitted particles is 5.6 g cm/sec for a typical case compared with the measured target impulse of 6.1 g cm/sec.