Interaction between a strong laser-ablation shock and a shock wave from the supersonic-to-subsonic transition of radiation

We present the results of an experiment carried out at the Omega laser facility to study the interaction between a strong (multi-Mbar) shock driven by direct laser ablation and a weaker shock induced by the supersonic-to-subsonic transition of radiation in silica (SiO₂) aerogel. The physics package is comprised of a silica foam cylinder exposed to a ~100 eV radiation drive created by a laser-driven halfraum, which induces a supersonic radiation front propagating axially into the cylinder. A counter-propagating shock is generated using directly laser-driven CH and Al foils which collides with the transitioning super-to-sub sonic shock. X-ray radiography shows the counter-propagation of both shocks and their interaction.  This process is observed in several high-energy-density experiments and our campaign demonstrates that it can be accurately simulated with the radiation hydrodynamic code KULL.

* This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344. LLNL-ABS-824594