A method for evaluating the mean preheat temperature in X-ray driven ablation

Abstract

A novel method is proposed for evaluating the mean preheat temperature in X-ray driven ablation, based on the equation of state (EOS) of the ablator and the radiation hydrodynamic simulation. The equation of state of plastic (CH) has been discussed in detail. There are two types of planar CH in simulations, with the thick target being 10 μm thicker than the thin target. The difference between the transmission fluxes of the two types of targets can represent the energy absorbed by the last 10 μm of the thick target (or the preheated layer). This energy approximates the internal energy of the preheated layer. The mean preheat temperature of the preheated layer has also been obtained from simulations. The simulation results show that the relationship between the absorbed energy and the mean preheat temperature is similar to the EOS of CH for different conditions (e.g., different values of M-band fraction and radiation temperature) and can be written as ε=2.530×1011T¯1.444 when the mean preheat temperature is below 12 eV. For these cases, the relationship between the surface preheat temperature TS and the mean preheat temperature T¯ was TS=0.63T¯. This relation provides the means for demonstrating the proposed method, because the transmission fluxes and the surface preheat temperature TS can be measured experimentally.