Analysis of microscopic magnitudes of radiative blast waves launched in xenon clusters with collisional-radiative steady-state simulations

Abstract

Radiative shock waves play a pivotal role in the transport energy into the stellar medium. This fact has led to many efforts to scale the astrophysical phenomena to accessible laboratory conditions and their study has been highlighted as an area requiring further experimental investigations. Low density material with high atomic mass is suitable to achieve radiative regime, and, therefore, low density xenon gas is commonly used for the medium in which the radiative shocks such as radiative blast waves propagate. In this work, by means of collisionalradiative steady-state calculations, a characterization and an analysis of microscopic magnitudes of laboratory blast waves launched in xenon clusters are made. Thus, for example, the average ionization, the charge state distribution, the cooling time or photon mean free paths are studied. Furthermore, for a particular experiment, the effects of the self-absorption and self-emission in the specific intensity emitted by the shock front and that is going through the radiative precursor are investigated. Finally, for that experiment, since the electron temperature is not measured experimentally, an estimation of this magnitude is made both for the shock shell and the radiative precursor.

Time-dependent and radiation field effects on collisional-radiative simulations of radiative properties of blast waves launched in clusters of xenon

“…Furthermore, in other previous works [21,22,23] we made an analysis of microscopic properties such as the monochromatic opacities and emissivities, mean opacities, optical depths, radiative power losses, cooling times, specific intensities and also a collisional-radiative diagnosis of the electron temperature for a particular experiment in which a blast wave was launched in a clustered gas of Xe irradiated by an intense laser [16]. All those simulations were performed solving a collisional-radiative model assuming steady state situation and without including the effect of the radiation coming from the shocked material in the radiative precursor.…”

“…The emissivity and the absorption coefficients ( j (r, t, ν) and κ (r, t, ν), respectively) couple the radiative equation with the rate equations. However, in this work they are uncoupled since as we obtained in [23] the plasma self-absorption can be neglected in the 3 calculation of plasma level populations both in the shocked material and in the radiative precursor regions and, besides, since in the analysis of the effect of the radiation in the kinetics calculations of the radiative precursor the Planck function is used to model the intensity of the radiation field.…”

“…In a previous work an estimation of the temperature of the shock front was made in local thermodynamic equilibrium (LTE), using Saha-Boltzmann (SB) equations, and in NLTE [23] but in steady-state (CRSS) situation. The procedure employed for that purpose was to generate a database of the average ionizations, both using the SB equations and the CRSS model, as a function of the electron densities and temperatures.…”

“…We have assumed that the shock shell is an homogeneous medium in which the source function does not vary with the location, with planar geometry of thickness D calculated as the full width at half maximum of the shocked shell, which is experimentally measured and is ranged between 86 μm (at 3 ns) and 167 μm (at 83 ns) [23]. Assuming I ν (0) = 0 in Eq.…”

“…First of all, we have studied the opacity of the radiative precursor for its density of matter and for the range of temperatures 1-10 eV which is the one that we estimated for the radiative precursor using the CRSS model in [23]. Thus, in Fig.…”