Investigation of the dynamics of converging shock waves in spherical and annular configurations

In a joint experiment between the IFAM-CNR, Pisa, and the Institute of Physics, Academy of Sciences, Tiblisi, we studied the converging motion and the collapse of annular and spherical shock waves. The radial converging motion of the waves was followed by holographic interferometry and shadowgraphy. The experimental measurements indicated the stability of the imploding shock wave in both annular and spherical configurations and showed that its amplitude, and consequently velocity, increases steeply as the wave approaches the axis of centre of symmetry, giving evidence for the cumulative nature of the motion. A one-dimensional simulation code for spherically symmetric converging shock waves is used to reproduce the radial change of the velocity of the waves in both cases. The simulation results are compared with the analytical treatment of the problem.