Self-Similar Multimode Bubble-Front Evolution of the Ablative Rayleigh-Taylor Instability in Two and Three Dimensions

Area of Science:

• Plasma physics
• Fluid dynamics
• Computational physics

Background:

• The ablative Rayleigh-Taylor instability (ARTI) is crucial in inertial confinement fusion.
• Understanding its nonlinear evolution is key to predicting implosion performance.
• Previous models often simplified the multimode dynamics and ablation effects.

Purpose of the Study:

• To numerically investigate the self-similar nonlinear evolution of multimode ARTI in 2D and 3D.
• To determine the scaling laws governing bubble-front penetration under ablation.
• To analyze the impact of initial conditions, ablation velocity, and vorticity on ARTI dynamics.

Main Methods:

• Numerical simulations in two and three dimensions.
• Analysis of bubble competition and merger regimes.
• Quantification of bubble velocity and penetration scaling.

Main Results:

• The nonlinear multimode bubble-front penetration follows the α_{b}A_{T}(∫sqrt[g]dt)^{2} scaling law.
• The coefficient α_{b} depends on initial conditions and ablation velocity, modified by mass ablation.
• Ablation-driven vorticity accelerates bubbles and can prevent merger, leading to higher α_{b} than classical predictions for large perturbations.

Conclusions:

• Mass ablation reduces α_{b} compared to classical values for similar initial perturbations.
• Vorticity generation significantly impacts ARTI, increasing bubble velocity.
• Ablative stabilization is less effective for large initial perturbations due to vorticity effects, contrary to prior expectations.