Pressure wave propagation in an imploding liquid metal liner

The propagation of a pressure wave through an imploding liquid metal liner near turnaround, due to the compression of magnetic flux and plasma is considered, based on which the pressure distribution near turnaround is derived analytically under the assumption of a small Mach number M (defined by the ratio between characteristic radial velocity of liner and the velocity of sound through the medium). It is shown that under certain conditions, the rarefaction wave from the outer (free) surface causes the apparition of a negative pressure in the imploding liner, with consequent liability of cavitation. The criterion for the generation of the negative pressure is found to be MΛ > 0.6 -- 0.7 for the range of parameters considered (Λ: liner thickness at turnaround normalized by the inner radius). (author)