Viscosity Control Experimental Design

Turbulent mix has been invoked to explain many results in Inertial Confinement Fusion (ICF) and High Energy Density (HED) physics, such as reduced yield in capsule implosions. Many simulations use fluid turbulent mix models to help match simulation results to data, but this is not appropriate if fully developed turbulence is not present. Mix, turbulent or not, can turn a plasma of a single material into a multi-component plasma, causing the viscosity to change by orders of magnitude depending on the fraction of high-Z material mixed in. Unlike fluids, mixed plasmas can have a change in viscosity that is high enough to ward off further turbulent growth. This effect is most pronounced for plasmas that are strongly coupled, where increases in high-Z dopant fraction can increase the viscosity by orders of magnitude. In contrast, the viscosity for ideal plasmas decreases with increasing Z as Z^-4. We discuss the development of experimental designs to measure the effect of viscosity on instability growth. Our ultimate goal is to conduct future experiments where instability growth or turbulent mixing could be turned on or off by changes in high-Z dopant concentration. This could lead to ways to mitigate turbulence in Omega and NIF implosions as well as other HED experiments.