Instability seeding mechanisms due to internal defects in inertial confinement fusion targets

Performance degradation in laser-driven inertial confinement fusion (ICF) implosions is caused by several effects, one of which is Rayleigh-Taylor instability growth. Defects in ICF targets, such as internal voids and surface roughness, create instability seeds in the shell as shocks propagate through the target. A comprehensive understanding of seeding mechanisms is essential to characterize the impact of target defects on inflight shell integrity and mass injection into the central, lower-density vapor region. An analysis of early-time behavior of both single-mode shell mass modulations and isolated voids is performed by examining the evolution of the acoustic waves launched by these target imperfections. A systematic study of localized perturbation growth as a function of defect placement and size is presented. The use of low-density ablator materials (such as foams) is suggested as a potential mitigation strategy to improve target robustness against the impact of defect-initiated growth.

Automated summary

This study focuses on the performance degradation in laser-driven inertial confinement fusion implosions. The causes of the degradation include Rayleigh-Taylor instability growth. Defects in the target lead to instability seeds and impact the shell integrity and mass injection. The early-time behavior of single-mode shell mass modulations and isolated voids is analyzed, and the growth of localized perturbations is studied in relation to defect placement and size.