Planar shock waves in liquids produced by high-energy KrF laser: A technique for studying hydrodynamic instabilities

Abstract

AbstractThe paper is devoted to research and development of a novel experimental technique—liquid-filled laser-driven shock tube (LST) for modeling of Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) hydrodynamic instabilities development at the contact surface of two immiscible liquids under shock wave (SW) passage. 100-J, 100-ns KrF laser facility GARPUN has been used to irradiate some opaque liquids. A homogenizing focusing system combined multi-element prism raster and a lens to provide non-uniformity less than a few percents across a square 7 × 7-mm spot, laser intensities being varied in the range of q = 0.004–2 GW/cm2. Surface plasma blow-off produced a planar SW, which propagated into the liquid. SW amplitudes as high as 0.8 GPa weakly damping with increasing thickness were measured in dibutyl-phthalate (DBP), which volumetrically absorbed ultraviolet (UV) laser light. Nonlinear absorption coefficients and laser breakdown thresholds were measured for pure water and UV optical materials intended to confine plasma. Test bench experiments were performed to produce standing acoustic waves as initial perturbations at the interface between two immiscible liquids.