Evaluation of shock propagation and preheat from non-Planckian x-ray source driven polystyrene based ablators

Abstract

The effect of non-Planckian radiation source is investigated in pure and 2% silicon doped polystyrene ablator foils by using radiation hydrodynamic simulations, covered over a broad range of drive parameters namely, its strength and hard or M-band x-ray contribution α (ratio of externally imposed Gaussian to original Planck energy density). The spatiotemporal dynamics of shock propagation indicates a large change in rear surface conditions, measured in terms of density and material temperature evolution with the increasing values of α and doping. Different scaling relations, motivated by the generalization of stationary x-ray driven ablation and strong shock theory, are proposed for different variables of interest that suggest a sharp and slow rise with strength and α of incident source, respectively. Just a 2% of silicon doping is able to increase the shock speed by ∼9% and, to reduce the shock breakout and the maximum preheating temperature by ∼40% and ∼50%, respectively for extreme drive conditions. A thorough understanding of the results is important in interpreting the present inertial confinement fusion experiments and proposing the next generation polystyrene based implosion designs for National Ignition Facility.