Control of Rayleigh–Taylor instabilities in laser accelerated seeded targets

Abstract

It is important to ameliorate the early time imprinting of nonuniformities due to laser radiation or target shell surface in an inertial confinement fusion (ICF) scheme. However, they will not prevent the instabilities which originate at the ablation surface due to acceleration of high density plasma by low density plasma. One of the methods discussed here is to combat the growth of instabilities at the ablation surface. The present work is aimed to control growth of hydrodynamic instability in laser irradiated target at moderate intensities. Laser (λ = 1.06 μm) radiation was focused on the plastic (base) target seeded with microinclusions of Al and Au at various concentrations. Targets had planar geometry and were of few microns in thickness. The target stability was studied using the optical backlighting technique. Shadowgrams of the seeded targets show a uniform motion of the target rear, whereas pure plastic targets break up under identical conditions. Results are analyzed by considering the X-radiation transport, coherent structure effects of the plasma like vortices, self-generated magnetic field in the accelerated target, and nonlinear conversion of long wavelength perturbation into short wavelength perturbation.