Nonlinear evolution of the ablative Rayleigh-Taylor instability with preheating

TL;DR

This paper numerically investigates how preheating length influences the nonlinear evolution of the ablative Rayleigh-Taylor instability, revealing different behaviors for weak and strong preheating conditions.

Contribution

It provides new insights into the nonlinear evolution of the ablative Rayleigh-Taylor instability considering preheating effects, highlighting the dependence on preheating length.

Findings

Weak preheating causes a sharp maximum in growth rate and secondary spike-bubbles.

Strong preheating results in elongated jets without secondary spike-bubbles.

Interaction of harmonic modes explains the different evolution patterns.

Abstract

Evolution of the single-mode ablative Rayleigh-Taylor instability in the presence of preheating is investigated numerically. It is found that the instability evolution depends strongly on the preheating length $L$ in front of the ablation-front interface. For weak preheating ($L/L_{\rm SH}\leq f_0$, where $L_{\rm SH}$ is the Spitzer-Harm length and $f_0\sim 20$ is a critical value), the linear growth rate has a sharp maximum and a secondary spike-bubble structure is generated. Interaction of this growing structure with the master spike-bubble leads to rupture of the latter. However, for strong preheating ($L/L_{\rm SH}>20$), the linear growth rate has no sharp maximum and no secondary spike-bubble is generated. Instead, the master spike-bubble evolves into an elongated jet. These results are interpreted in terms of the evolution and interaction of the instability-generated harmonic modes.