A project based on multi-configuration Dirac–Fock calculations for plasma spectroscopy

Abstract

We present a project dedicated to hot plasma spectroscopy based on a Multi-Configuration DiracFock (MCDF) code, initially developed by J. Bruneau. The code is briefly described and the use of the transition state method for plasma spectroscopy is detailed. Then an opacity code for localthermodynamic-equilibrium plasmas using MCDF data, named OPAMCDF, is presented. Transition arrays for which the number of lines is too large to be handled in a DLA calculation can be modeled within the Partially Resolved Transition Array method or using the Unresolved Transition Arrays formalism in jj-coupling. An improvement of the original Partially Resolved Transition Array method is presented which gives a better agreement with Detailed Line Accounting computations. Comparisons with some absorption and emission experimental spectra are shown. Finally, the capability of the MCDF code to compute atomic data required for collisional-radiative modeling of plasma at non local thermodynamic equilibrium is illustrated. Additionally to photoexcitation, this code can be used to calculate photoionization, electron impact excitation and ionization cross-sections as well as autoionization rates in the Distorted-Wave or Close Coupling approximations. Comparisons with cross-sections and rates available in the literature are discussed.

Comparison of Iron Plasma Atomic and Radiative Properties Computed with a Relativistic Collisional Radiative Average Atom Code versus Other Models

“…15-18 there are displayed spectra of frequency resolved transmission of iron plasmas, checking the high spectral quality of ATMED CR with respect to other atomic codes [35][36][37][38], as well as the high sensitivity to slight [27] at 0.0001 g/cm 3 ) and K P (■) mean are similar to those of…”

“…Fe experimental transmission (Da Silva 1992) compared to OPAL, OP [35]Fe experimental transmission compared to codes OPAMCDF, SCO-RCG[37,38] and , 150 eV, 54 μg/cm 2 , corresponding to plasma length of 9.…”

Detailed Opacity Calculations for Stellar Models

“…[Iglesias & Sonnad (2012)] remove the passive subshells from the "real" configuration whichever their population. In fact, this can be improved by taking into account that the electrons in a subshell can be removed "one by one" [Comet et al (2017b)]. On the other hand, if there is at least one electron in the second part (highly-excited configurations), transition arrays are calculated in the SOSA formalism, relying on an efficient direct computation of the two-electron relativistic strength-weighted mean and variance of the line energies [Krief & Feigel (2015)].…”

“…The detailed opacity code SCO-RCG for local-thermodynamic-equilibrium (LTE) plasmas is described in Section 2, as well as the OPAMCDF project [Comet et al (2017a), Comet et al (2017b)] dedicated to the spectroscopy of LTE and non-LTE plasmas. The interpretations of some laser and Z-pinch experiments are presented in Section 3, and the modeling of the Sun interior is discussed in Section 4.…”

Comment on electron-impact excitation cross section measurements for He-like xenon

“…[1,3], we (J.-C. Pain and M. Comet) performed DW computations with our Multi-Configuration Dirac-Fock (MCDF) code [5][6][7][8] for the lines Ly α1 (1s 2 S 1/2 → 2p 2 P 3/2 ), Ly α2,3 (1s 2 S 1/2 → 2p 2 P 1/2 , and 1s 2 S 1/2 → 2s 2 S 1/2 ) in the case of H-like Xe 53+ , and for the lines w (1s2p 1 P 1 → 1s 2 1 S 0 ) and y (1s2p 3 P 1 → 1s 2 1 S 0 ) in the case of He-like Xe 52+ . For atoms with two or more electrons, the Breit interaction, and more recently the generalized Breit interaction, which is described by a complex function, can be included in the matrix elements of collisional processes [9][10][11][12][13][14][15].…”