Effect of preheating on the nonlinear evolution of the ablative Rayleigh-Taylor instability

The evolution of the ablative Rayleigh-Taylor instability in the presence of preheating of the cold pristine plasma ahead of the ablative front is investigated by two-dimensional numerical simulation. When the dependence of the linear ARTI growth rate on the excitation wavelength has a sharp maximum, a secondary spike-bubble structure at a harmonic of the excitation wavelength will be generated, leading to rupture of the original mode. On the other hand, for stronger preheating the linear growth rate has no sharp maximum and in the nonlinear evolution no competing secondary spike-bubble structure is generated. Instead, the original excitation evolves into an elongated jet. These results are in agreement with that from an analytical single-mode theory.