Three-dimensional modeling and hydrodynamic scaling of National Ignition Facility implosions

Abstract

The goal of an inertially confined, igniting plasma on the National Ignition Facility (NIF) [M. L. Spaeth, Fusion Sci. Technol. 69, 25 (2016)] remains elusive. However, there is a growing understanding of the factors that appear to be limiting current implosion performance. And with this understanding, the question naturally arises: What conditions will ultimately be required to achieve ignition, either by continuing to improve the quality of current implosions, or by hydrodynamically scaling those implosions to larger driver energies on some future facility? Given the complexity of NIF implosions, answering this question must rely heavily on sophisticated numerical simulations. In particular, those simulations must respect the three-dimensionality of real NIF implosions and also resolve the wide range of scales for the many perturbation sources that degrade them. This prospectus article reviews the current state of detailed modeling of NIF implosions, the scaling to ignition from recent experiments that that modeling implies, and areas for future improvements in modeling technique that could increase understanding and further enhance predictive capabilities. Given the uncertainties inherent in any extrapolation, particularly for a process as nonlinear as ignition, there will be no definitive answer on the requirements for ignition until it is actually demonstrated experimentally. However, with continuing improvements in modeling technique and a growing experience base from NIF, the requirements for ignition are becoming clearer.