Movement of ablated high-<i>Z</i> plasmas

Abstract

The energy leaking through a slot in the hohlraum filled with low-&lt;i&gt;Z&lt;/i&gt; foams is a typical dynamic problem of the ablated high-&lt;i&gt;Z&lt;/i&gt; plasmas. In this paper, we develop a simplified one-dimensional model to study the expansion-reverse process of the ablated Au plasmas, which corresponds to the closing-reopening process of a slot. Our work shows that its physical mechanism is the ablation pressure competing with radiation pressure difference and the material pressure of low-&lt;i&gt;Z&lt;/i&gt; foams. The analytical formulas for the reverse time and reverse distance of the Au plasma are deduced, respectively, indicating that the cubic value for each of both peak temperatures is proportional to the density of the low-&lt;i&gt;Z&lt;/i&gt; foams. The main conclusions of analytic theory are verified by numerical simulation through using the modified radiation-hydrodynamic program MULTI. It is shown that the power exponents of scaling law in high-&lt;i&gt;Z&lt;/i&gt; plasma ablation keep unchanged in a wide range of density of low-&lt;i&gt;Z&lt;/i&gt; foams. The range of validity of the model is discussed.

Surface Tension of the Black Hole Horizon

“…The local thermal equilibrium is an important assumption in both Verlinde's entropic gravity [38] and Jacobson's thermodynamic derivation of the Einstein equation [49]. Moreover, it is also a basic assumption in a thin film model (also referred as a membrane model) provided by Zhao and his coworkers [50][51][52] by improving 't Hooft's brick-wall model [53] in order to calculate the statistical entropies of nonstatic black holes or black holes in nonthermal equilibrium. It was found that the local equilibrium near the horizon should be maintained for the black holes with a mass far greater than the Planck scale [48].…”