Super-spherical cumulation: shock collapse which is more intense than the spherical one

A shock wave implosion in an axisymmetric chamber with a convex bounding wall is studied experimentally, analytically and numerically. The converging shock front area in this geometry shrinks quickly as the shock wave approaches the center point. The analytical theory predicts that the corresponding rate of post-shock pressure and density increase in this case exceeds essentially that achieved in the classical cylindrical or spherical shock implosions, hence, the phenomenon is referred to as “super-spherical cumulation”. The experiments confirm higher intensity of the super-spherical implosion compared with the cylindrical one, both driven by identical high-current pulsed electric discharges. The converging shock stability is analyzed in the framework of the CCW theory. The numerical results obtained using a locally-adaptive unstructured grid technique agree well with the theoretical predictions of the converging shock wave intensity.