HYDRODYNAMIC INSTABILITY IN AN ABLATIVELY IMPLODED TARGET IRRADIATED BY HIGH-POWER GREEN LASERS

Time evolution of the ablation front displacement between concave and convex regions of a surface corrugated spherical target was observed by flash x-ray radiography. The results are compared with calculations based on the linearized fluid equation combined with a one-dimensional simulation to describe the ambient fluid motion. In the analysis, perturbation of the fluid is scaled up to kδ ~ 2π (k is the perturbation wavenumber and δ is the perturbation amplitude) for the acceleration phase with perturbation mode numbers of l = 20 and 30. The practical perturbation of the target requires a relaxation time to form the nominal eigenstate of the Rayleigh-Taylor instability, which results in time delay of instability growth onset. © 1988 American Institute of Physics.