Two-Dimensional Computational Model of Energy Gain in NIF Capsules

A two-dimensional hydrodynamic code is employed to describe the implosion of a NIF-like ICF capsule beginning from the free-fall phase to determine its energy gain. Data are taken from one-dimensional code LILAC at the end of the acceleration phase, and singleor multimode perturbations are then introduced in the inner shell surface. The data are then input into a twodimensional hydrodynamic code employing a uniformly moving mesh, the motion of which is determined by the trajectory of the capsule shell. Energy gain is then analyzed as a function of the pertubation amplitude for single-mode perturbations or of the mean-square perturbation amplitude for multimode perturbations. Alpha-particle energy deposition is treated diffusively in this model using a single energy group for faster computation.