Exploring the Landau-Darrieus instability in High Energy Density conditions on NIF: experimental design and preparatory experiments

Recent experimental work is presented which was designed to observe the Landau-Darrieus Instability (LDI) for the first time in the context of laser-driven ablation fronts. The most recent experiments were conducted at the National Ignition Facility (NIF) and build upon previous work conducted at OMEGA EP. To avoid stabilizing the LDI, the conduction zone length D$_{\mathrm{c}}$must be smaller than the studied wavelength. This is done by reducing the drive intensity. To maximize ablation velocity and maintain adequate growth rates, low-density foams are used. Finally, to prevent the Rayleigh-Taylor instability from dominating the system while still maximizing the growth of the LDI, thick targets with long drive durations are fielded. The analysis of the OMEGA EP experiment is presented here which critically informs the subsequent design and interpretation of the recent NIF results.