Opacity Measurement and Theoretical Investigation of Hot Silicon Plasma

Abstract

We report on opacity measurements of a silicon (Si) plasma at a temperature of (72 ± 5) eV and a density of (6.0 ± 1.2) mg cm −3 in the photon energy range of 1790-1880 eV. A 23 μg cm −2 Si foil tamped by 50 μg cm −2 CH layers on each side was heated to a hot-dense plasma state by X-ray radiation emitted from a D-shaped gold cavity that was irradiated by intense lasers. Absorption lines of 1s − 2p transitions of Si XIII to Si IX ions have been measured using point-projection spectroscopy. The transmission spectrum of the silicon plasma was determined by comparing the light passing through the plasma to the light from the same shot passing by the plasma. The density of the Si plasma was determined experimentally by side-on radiography and the temperature was estimated from the radiation flux data. Radiative hydrodynamic simulations were performed to obtain the temporal evolutions of the density and temperature of the Si plasma. The experimentally obtained transmission spectra of the Si sample plasma have been reproduced using a detailed term account model with the local thermodynamic equilibrium approximation. The energy levels, oscillator strengths and photoionization cross-sections used in the calculation were generated by the flexible atomic code. The experimental transmission spectrum was compared with the theoretical calculation and good agreement was found. The present experimental spectrum and theoretical calculation were also compared with the new opacities available in the Los Alamos OPLIB database.

Detailed Opacity Calculations for Astrophysical Applications

“…With the HETGS, silicon absorption lines were observed in the spiral galaxy NGC 3783, in the black hole candidate Cygnus X-1, in the ultracompact X-ray Dipper 4U 1916-05, in the Seyfert 1 galaxy NGC 5548, in the bright Seyfert 1 galaxy MCG 6-30-15 and NGC 3516, in the Seyfert 1 active galactic nucleus NGC4051, etc. [65]. Silicates are an important component of cosmic matter [66].…”

Calculation of atomic structures and radiative properties of fusion plasmas

“…Nous allons maintenant nous intéresser aux résultats expérimentaux menés par Xiong et al [57]. Il s'agit ici d'un plasma de silicium à la température T e = 72 ± 5 eV et à la densité ρ = 6.0 ± 1.2 mg.cm −3 .…”

“…Dans la figure 10 de la Réf. [57], on constate que les auteurs rencontrent le même problème, que ce soit avec le code ATOMIC ou leur calcul avec la méthode DTA.…”

“…Les résultats sont très satisfaisants, aussi bien à l'ETL qu'hors-ETL. Nous avons aussi comparé nos résultats à la transmission mesurée par Xiong et al [57] d'un plasma de silicium à T e = 72 eV et n e = 1.3 × 10 21 cm −3 . Là encore, nous obtenons un bon accord.…”

Effects of lowly ionized ions on silicon K-shell absorption spectra

“…For other light elements, extensive experiments were also conducted in laboratories (Davidson et al 1988;Perry et al 1991;Xiong et al 2016). Most of these above experiments measured the opacity at an order of 0.001 to 0.1 g/cm −3 , which is corresponding to an electron density of order from ∼10 20 cm −3 to ∼10 22 cm −3 .…”