Radiation effects on hydrodynamic perturbation growth due to non-uniform laser irradiation

Abstract

The initial imprint caused by the spatial non-uniformity of laser intensity which generates a mass perturbation is one of the critical issues for directly driven laser fusion research. To mitigate such laser imprint a foam-hybrid target, which has low-density foam layer and is coated with high- Z material, was proposed. In such targets, the X-ray radiation plays a significant role in the formation of the initial imprint. For short wavelength perturbations, a clear suppression of the perturbation growth is observed in the foam-hybrid target. The perturbation growth is reduced by radiation preheating since the ablation surface is smoothed. Moreover, the emitted X-rays from the coated high- Z material suppresses the hydrodynamic instability at the interface of plastic and foam. However, the ablation structure is sensitive to the opacity model. Thus, it is important to analyze the role different radiation models play in the hydrodynamics. In this work we will compare both CRE and LTE models.