Characterization of the ballistic properties of ejecta from laser shock-loaded samples using high resolution picosecond imaging

摘要

A high resolution picosecond laser imaging diagnostic has been developed for making high-resolution spatial measurements of ejecta particles moving at high velocities (a few km/s). Preliminary results obtained with both visible (532 run) and UV (355nm) lighting were presented for laser shock-driven ejecta experiments performed on 100 μm thick Sn targets, with vertical grooves of different shape in their free surface. A comparison with ns laser imaging performed in similar conditions highlights the necessity of sub-nanosecond lighting if one wants to capture the movement of the fastest ejecta with typical velocities of a few km.s～(-1) without any motion blur. The microsheet breakup process observed with both visible and ultraviolet lighting is in good agreement with the three stages breakup process first evidenced by Sorenson et al. at LANL [19-20], using ultraviolet in-line Fraunhofer holography, and also observed in MD simulations [21-24].