Flow Instability: Richtmyer-Meshkov and Pulsating Flows

The Richtmyer-Meshkov instability (RMI) arises when a shock crosses an interface between two disparate density materials. In inertial confinement fusion (ICF) capsules, this occurs between the outer heavy material (the ablator) and the light fuel layer. The result is mixing of heavy ablator material into the light fuel layer, leading to a degradation of yield. To better understand this instability, Los Alamos National Laboratory performs experiments using the Vertical Shock Tube (VST). The VST traditionally studies the growth of RMI between an air-SF6 interface. However, it is difficult for these experiments to lead to a potentially turbulent, layer. To study bypass the transition to turbulence, a grid is inserted into the VST experiment. A shock is used to accelerate air and SF6 through the grid, leading to grid generated turbulence. The reflected shock from the bottom of the experiment is then used to study shocked Richtmyer-Meshkov instability. Results from recent experiments will be presented.

Funding acknowledgement

This work was supported by the U.S. Department of Energy through the Los Alamos National Laboratory. Los Alamos National Laboratory is operated by Triad National Security, LLC, for the National Nuclear Security Administration of U.S. Department of Energy (Contract No. 89233218CNA000001).