The Los Alamos suite of relativistic atomic physics codes

Abstract

The Los Alamos suite of relativistic atomic physics codes is a robust, mature platform that has been used to model highly charged ions in a variety of ways. The suite includes capabilities for calculating data related to fundamental atomic structure, as well as the processes of photoexcitation, electron-impact excitation and ionization, photoionization and autoionization within a consistent framework. These data can be of a basic nature, such as cross sections and collision strengths, which are useful in making predictions that can be compared with experiments to test fundamental theories of highly charged ions, such as quantum electrodynamics. The suite can also be used to generate detailed models of energy levels and rate coefficients, and to apply them in the collisional-radiative modeling of plasmas over a wide range of conditions. Such modeling is useful, for example, in the interpretation of spectra generated by a variety of plasmas. In this work, we provide a brief overview of the capabilities within the Los Alamos relativistic suite along with some examples of its application to the modeling of highly charged ions.

Mass selection in laser-plasma ion accelerator on nanostructured surfaces

“…ATOMIC is a multi-purpose plasma kinetics code 28,29 that is used for modelling local thermodynamic equilibrium (LTE) and non-LTE plasmas, and can predict ionization balances, opacities and emissivities for a wide range of plasma conditions. The code takes as input atomic structure and collision data from the Los Alamos suite of atomic physics codes (for an overview, see 30 ). In this case, the CATS code 31,32 was used in configuration-average mode to generate structure data and electron-impact excitation cross-sections for all ionization stages of Cu.…”

“…In this case, the CATS code 31,32 was used in configuration-average mode to generate structure data and electron-impact excitation cross-sections for all ionization stages of Cu. The GIPPER code 30,33 was then used to generate all possible ionization cross-sections. ATOMIC was run in steady-state non-LTE mode 34 (assuming zero radiation temperature) and used the electron temperature, density values and the initial average charge of the ions starting from the surface of the solid target produced by HYADES as input, resulting in predictions of the average ionization and charge distribution at each set of plasma conditions.…”

Photoionization of Co+and electron-impact excitation of Co2 +using the DiracR-matrix method

“…The results in this figure have been convoluted with a 10 meV Gaussian profile at fullwidth half-maximum to better compare with experiment. We directly compare here with the results of all three previously mentioned theoretical methods (Reilman & Manson 1979;Verner et al 1993;Fontes et al 2015). These methods do not include autoionization states and therefore only background cross-sections are presented.…”

Opacity Measurement and Theoretical Investigation of Hot Silicon Plasma

“…It is hard to perform a complete CI calculation between all of the configurations. In fact, within the same configuration the mixing between all basic states was included (i.e., intermediate coupling Fontes et al 2015), whereas only the CI between the ground and the first excited configurations was allowed. The accuracy of the atomic data is crucial for the final shape of the transmission spectrum.…”

“…Later on, the DCA method was much improved with a new detailed term accounting (DTA) OPLIB database, with the opacity tables generated by the LEDCOP code (Magee et al 1995). More recently, the data produced by the newest ATOMIC code (Colgan et al 2013b;Fontes et al 2015) have been released in the OPLIB database. 4 Lawrence Livermore National Laboratory (LLNL) has developed a stellar opacity model using the DTA method called OPAL (Rogers & Iglesias 1992).…”