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{We aim to demonstrate the effect of atmospheric inhomogeneities on the emergent specific intensity and radiation flux of a spectral line radiation.} {We self-consistently solve the NLTE problem for a two-level atom in a 3D atmosphere using…

Solar and Stellar Astrophysics · Physics 2019-01-08 A. Tichý , J. Kubát

Weakly collisional and collisionless plasmas are typically far from local thermodynamic equilibrium (LTE), and understanding energy conversion in such systems is a forefront research problem. The standard approach is to investigate changes…

Plasma Physics · Physics 2023-06-05 Paul A. Cassak , M. Hasan Barbhuiya , Haoming Liang , Matthew R. Argall

X-Ray transition energies and isotope shifts in heavy atoms are evaluated. The energy levels with vacancies in the inner shells are calculated within the approximation of the average of nonrelativistic configuration employing the…

Atomic Physics · Physics 2018-08-29 I. I. Tupitsyn , N. A. Zubova , V. M. Shabaev , G. Plunien , Th. Stoehlker

The present work proposes a self-consistent reduced-order NLTE kinetic model for radiating plasmas such as are found in the outer layers of stellar atmospheres. Starting from the most up-to-date set of ab-initio and experimental data, the…

Solar and Stellar Astrophysics · Physics 2017-04-12 A. Munafo , N. Mansour , M. Panesi

A general formalism for the treatment of density fluctuations in Coulomb plasmas is presented and applied to the treatment of temperature relaxation in multi-component quantum plasmas when the separate components (electrons and ions) relax…

Plasma Physics · Physics 2015-10-06 Basil Crowley

The synthetic emission spectra and opacity of high-density, high-temperature germanium (Z=32) plasma from super-transition-array (STA) calculations are presented. The viability of the STA model, which is based on a statistical…

The calculation of line widths constitutes theoretical and computational challenges in the calculation of opacities of hot dense plasmas. Opacity models use line broadening approximations that are untested at stellar interior conditions.…

Solar and Stellar Astrophysics · Physics 2016-06-22 M. Krief , A. Feigel , D. Gazit

In a dense plasma environment, the energy levels of an ion shift relative to the isolated ion values. This shift is reflected in the optical spectrum of the plasma and can be measured in, for example, emission experiments. In this work, we…

Plasma Physics · Physics 2024-09-11 T. Q. Thelen , D. A. Rehn , C. J. Fontes , C. E. Starrett

Charge state distributions in hot, dense plasmas are a key ingredient in the calculation of spectral quantities like the opacity. However, they are challenging to calculate, as models like Saha-Boltzmann become unreliable for dense, quantum…

Plasma Physics · Physics 2024-06-19 J. White , W. Johns , C. J. Fontes , N. M. Gill , N. R. Shaffer , C. E. Starrett

The growing interest in atomic structures of moderately-stripped alkali-like ions in diagnostic study and modeling of astrophysical and laboratory plasma makes an accurate many-body study of atomic properties inevitable. This work presents…

Atomic Physics · Physics 2023-03-30 Swapan Biswas , Anal Bhowmik , Arghya Das , Radha Raman Pal , Sonjoy Majumder

We introduce and test a new and highly efficient method for treating the thermal and radiative effects influencing the energy equation in SPH simulations of star formation. The method uses the density, temperature and gravitational…

Astrophysics · Physics 2009-11-13 D. Stamatellos , A. P. Whitworth , T. Bisbas , S. Goodwin

Analysis of high-resolution stellar spectra relies heavily upon atomic data. These include energy levels, wavelengths, cross-sections for various types of interactions between particles and photons, such as photoionization and collision…

Solar and Stellar Astrophysics · Physics 2011-04-12 Maria Bergemann

The broadening of lines by Stark effect is widely used for inferring electron density and temperature in plasmas. Stark-effect calculations often rely on atomic data (transition rates, energy levels,...) not always exhaustive and/or valid…

Atomic Physics · Physics 2017-04-05 Jean-Christophe Pain , Franck Gilleron , Maxime Comet , Dominique Gilles

The self-energy and the vertex radiative corrections to the effect of parity nonconservation in heavy atoms are calculated analytically in orders Z alpha^2 and Z^2 alpha^3 ln(lambda_C/r_0), where lambda_C and r_0 being the Compton…

High Energy Physics - Phenomenology · Physics 2009-11-07 A. I. Milstein , O. P. Sushkov , I. S. Terekhov

We consider three recent large-scale calculations for the radiative and electron-impact excitation data of N IV, carried out with different methods and codes. The scattering calculations employed the relativistic Dirac $R$-matrix (DARC)…

Solar and Stellar Astrophysics · Physics 2019-02-20 G. Del Zanna , L. Fernandez-Menchero , N. R. Badnell

We tabulate spontaneous emission rates for all possible 811 electric-dipole-allowed transitions between the 75 lowest-energy states of Ca I. These involve the $4sns$ ($n=4-8$), $4snp$ ($n=4-7$), $4snd$ ($n=3-6$), $4snf$ ($n=4-6$), $4p^2$,…

Atomic Physics · Physics 2017-11-22 Yanmei Yu , Andrei Derevianko

Predictive simulations of mixed plasma discharges, like deuterium-tritium plasmas, rely on self-consistent models for particle transport. These models have to be validated with interpretive analysis of existing experiments. Accounting for…

The analysis and modelling of a range of plasmas (for example: astrophysical, laser-produced and fusion), require atomic data for a number of parameters, such as energy levels, radiative rates and electron impact excitation rates, or…

Atomic Physics · Physics 2017-10-09 K. M. Aggarwal

For the reliable analysis and modelling of astrophysical, laser-produced and fusion plasmas, atomic data are required for a number of parameters, including energy levels, radiative rates and electron impact excitation rates. Such data are…

Instrumentation and Methods for Astrophysics · Physics 2013-01-15 Km Aggarwal , Fp Keenan

A self-consistent approach to nonequilibrium radiation temperature is introduced using the distribution of the energy over states. We begin rigorously with ensembles of Hilbert spaces and end with practical examples based mainly on the far…

Statistical Mechanics · Physics 2009-11-07 Christopher Essex , Dallas C. Kennedy , R. Stephen Berry