Detailed-term-accounting approximation calculations of the radiative opacity of aluminum plasmas: A systematic study

Abstract

The spectrally resolved radiative opacity and the Rosseland and Planck mean opacities are calculated by using the detailed-term-accounting approximation for aluminum plasmas with varieties of density and temperature. The results are presented along a 40 eV isothermal sequence, a 0.01 g/cm(3) isodense sequence, and a sequence with average ionization degree Z* approximately 7.13. Particular attention is given to the influence of the detailed treatment of spectral lines on the Rosseland mean opacity under different thermodynamic conditions. The results show that at densities of 0.004 g/cm(3) and higher, the opacities are not very sensitive to the spectral linewidth within a reasonable range. As examples, the Rosseland mean opacity, which is most sensitive to the detailed linewidth, at 40 eV and 0.004 g/cm(3) changes no more than 15%, when we change the electron impact spectral linewidth artificially by reducing it by 50% or increasing it twice, and at 40 eV and 0.1 g/cm(3) it changes less than 5%. For comparison, we also carried out calculations by using an average atom model. For the Rosseland mean opacities, the two models show quite large differences, in particular at low densities, while for the Planck mean opacities the results of the two models are much closer.

Radiative opacity of plasmas studied by detailed term (level) accounting approaches

“…In the photon energy range shown in the plot, the Stark width is much more larger than the Doppler width, thus the Stark broadening is the major broadening mechanism. As we have demonstrated in a recent paper [37], the Planck mean opacities are nearly equal with and without considering the Stark width, but the Rosseland mean opacities differ consid erably depending on whether or not the Stark broadening is taken into account. The Rosseland mean opacities are sensitive to the detailed profile and corresponding width.…”

Analysis of the influence of the plasma thermodynamic regime in the spectrally resolved and mean radiative opacity calculations of carbon plasmas in a wide range of density and temperature

“…And, finally, the collisional broadening is given by r" (n'-'H-1 )' (7) where n e is the electron density, m e is the electron mass, ¡i running over the relativistic orbitals involved in the transition, and finally, n and / are the principal and angular quantum number of the orbitals, respectively.…”

“…Due to its relevance, research on radiative opacities has greatly developed during the past several decades, though most of them were focused on Local Thermodynamic Equilibrium (LTE) regime [3][4][5][6][7][8]. However, NonLocal Thermodynamic Equilibrium (NLTE) plasmas are found in a wide range of density and temperature conditions as for example in inertial confinement fusion (both direct and indirect-drive fusion schemes), in magnetic confinement fusion (both in tokamaks and stellarator devices), z-pinch plasmas, coherent X-ray sources, ultrashort pulse laser-produced plasmas or stellar atmospheres.…”

“…However, the complexity of the rate equations, which requires a huge amount of atomic data and collisional and radiative atomic processes, makes much more difficult to give accurate level populations and radiative properties for NLTE plasmas than for LTE ones. For this reason, during the recent years many groups have been developing NLTE radiative properties calculations and codes [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], and new models and results are always welcomed.…”

Opacity calculation for target physics using the ABAKO/RAPCAL code

“…Since SahaBoltzmann equations overestimate the average ionization with respect to the CR calculations, the mean opacities in the latter model are always greater than in the former. This is shown in Table 4, where the results assuming LTE are given, and they have been compared with those obtained in LTE from other authors [37].…”