Abstract

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