Experimental observations on the links between surface perturbation parameters and shock-induced mass ejection

Abstract

We have assembled together our ejecta measurements from explosively shocked tin acquired over a period of about ten years. The tin was cast at 0.99995 purity, and all of the tin targets or samples were shocked to loading pressures of about 27 GPa, allowing meaningful comparisons. The collected data are markedly consistent, and because the total ejected mass scales linearly with the perturbations amplitudes they can be used to estimate how much total Sn mass will be ejected from explosively shocked Sn, at similar loading pressures, based on the surface perturbation parameters of wavelength and amplitude. Most of the data were collected from periodic isosceles shapes that approximate sinusoidal perturbations. Importantly, however, we find that not all periodic perturbations behave similarly. For example, we observed that sawtooth (right triangular) perturbations eject more mass than an isosceles perturbation of similar depth and wavelength, demonstrating that masses ejected from irregular shaped perturbations cannot be normalized to the cross-sectional areas of the perturbations.

Mass-velocity and size-velocity distributions of ejecta cloud from shock-loaded tin surface using atomistic simulations

“…Typically, pressures of ~ 27 GPa were obtained with explosively driven experiments in references [7][8][9][10][11][12][13][14]. Therefore, what seems the most informative for us is to compare our results with some recently developed ejecta models [1,19], based on the nonlinear evolution of RMI [1,19].…”

“…Indeed, our Sn crystal is driven to a very high supported shock wave pressure (P > 60 GPa) to reach directly Sn liquefaction (and avoid in particular to deal with melting in release kinetics); and experimentally, such high pressure cannot be reached either by powder gun (supported shock-waves) or high explosive (unsupported shock-waves) experiments [14].…”

“…Experimentally and numerically, the ejecta cloud has been and continues to be characterized mainly globally, at the continuum level, through the measure of the total amount of ejected mass as a function of the velocity [7][8][9][10][11][12][13][14][15][16] and by using the conservation laws of hydrodynamics in computations [1,[17][18]. From these studies, is now well admitted that the phenomenon is a limiting case of Richtmyer-Meshkov instabilities (RMIs) [1,[19][20].…”

“…Relatively few data are available [21][22][23], and ongoing and long-term developments of specific tools [14,24] have to be undertaken. Theoretically and numerically, if it seems possible to estimate a distribution of characteristic particle sizes for small sinusoidal perturbations [16,20], models and hydrocodes fail for the moment to provide correlation between size and velocity of the particles inside the cloud.…”

Foreword to the Special Issue on Ejecta

“…Studies of the ejecta source also continued, with a report of work on Pb [49], and more results from the LANL Sn work [50]. The LANL source term work was extended to ejecta from a second shockwave [51,52], and the full LANL Sn ejecta set for supported and unsupported shock loading at a single finish was released [53,54].…”