Hydrodynamic evolution of laser driven diverging shock waves

Spherically symmetric shock waves have been produced via Nd3+ laser induced breakdown in helium, nitrogen and air at pressures ranging from 760 Torr to 2300 Torr. The measurements are performed at different absorbed laser energies (E0 = 0.05 J to 2 J) at the center of the experimental spherical glass cell where the breakdown of the gas takes place. The temporal evolution of the shock wave followed by a double-pulse, double-wavelength holographic techniques is described hydrodynamically well by the point strong explosion theory. The experimental data on temporal evolution of the density jump of the gas and the corresponding theoretical profiles obtained adopting a non-self-similar solution at the same laser absorbed energy are found to be in good mutual agreement.