Opacity calculations in X and XUV range using a detailed atomic code
Résumé
Calculations of accurate opacities in X and XUV range are of high interest for several domains such as astrophysics or inertial fusion science. Such quantities may be investigated through laser‐plasma interaction in the indirect‐drive scheme. In this work absorption properties of such plasmas are analysed using the Flexible Atomic Code. Detailed and unresolved‐transition‐array modes are investigated, and some results obtained with the mixed mode recently developed are also proposed. For a carbon plasma the present approach agrees with the results obtained with the superconfiguration code SCO. Some results are provided about the X‐ray opacity of nickel, and a comparison with data from a recent campaign on LULI 2000 facility is done. This comparison demonstrates that the Unresolved Transition Array approach may be insufficient, e.g., to determinate the accurate position and shape of the 2p–3d structure in nickel at about 25 eV. The case of non‐electric‐dipole‐type transitions, such as magnetic dipole transitions is addressed. The electric‐dipole and magnetic‐dipole transitions are studied here in the case of the 3 * n complex of five tungsten ions, with charge states similar to those found in the tokamak divertors. It is demonstrated that the unresolved transition array formulas provide a fairly accurate description of the most important absorption structures, but fail to reproduce correctly the behavior of the opacity in the wings of these main structures.