Time-dependent calculations of electron energy distribution functions for neon gas in the presence of intense XFEL radiation

Abdallah, J.; Colgan, J.; Rohringer, Nina

doi:10.1088/0953-4075/46/23/235004

Cited by 12 publications

(6 citation statements)

References 27 publications

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“…To overcome this difficulty, the existing continuum approaches, e.g., [15], use a superconfiguration scheme which does not follow the evolution of individual configurations but instead uses a simplified set of "average" configurations [16][17][18][19]. Here, we propose an alternative approach which uses "true" atomic configurations but limits their number by restricting the sample relaxation to predominant relaxation paths.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Boltzmann approach adapted for modeling highly ionized matter created by x-ray irradiation of a solid

et al. 2016

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We report on the kinetic Boltzmann approach adapted for simulations of highly ionized matter created from a solid by its x-ray irradiation. X rays can excite inner-shell electrons, which leads to the creation of deeply lying core holes. Their relaxation, especially in heavier elements, can take complicated paths, leading to a large number of active configurations. Their number can be so large that solving the set of respective evolution equations becomes computationally inefficient and another modeling approach should be used instead. To circumvent this complexity, the commonly used continuum models employ a superconfiguration scheme. Here, we propose an alternative approach which still uses "true" atomic configurations but limits their number by restricting the sample relaxation to the predominant relaxation paths. We test its reliability, performing respective calculations for a bulk material consisting of light atoms and comparing the results with a full calculation including all relaxation paths. Prospective application for heavy elements is discussed.

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Section: Introductionmentioning

confidence: 99%

Kinetic Boltzmann approach adapted for modeling highly ionized matter created by x-ray irradiation of a solid

et al. 2016

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“…If we assume the produced free electrons are instantaneous equilibrium, then the EEDF is a Maxwellian distribution function (named Maxwellian model in this work) [44]. In principle, the electron kinetics can be determined by solving the Boltzmann equation of free electrons [47]. Here we propose a relaxation time approximation to treat the electron-electron impact process, where the fraction of the relaxed electrons is assumed to reach equilibrium instantaneously.…”

Section: Theoretical Methodsmentioning

confidence: 99%

“…In this work, we systematically investigate the emission properties of DCH states of transient neon plasmas created in the interaction of XFELs with photon energy ranging from 937 eV to 2000 eV. A time-dependent rate equation (TDRE) approach [23,25,26] based on the collisional-radiative model is employed to study the evolution dynamics of charge state distribution (CSD) and emission properties. A detailed level accounting (DLA) model is utilized to describe the quantum states of the neon system.…”

Section: Introductionmentioning

confidence: 99%

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Single- and double-core-hole ion emission spectroscopy of transient neon plasmas produced by ultraintense x-ray laser pulses

Cheng

Zeng

Yuan

2016

J. Phys. B: At. Mol. Opt. Phys.

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Double core-hole (DCH) spectroscopy is investigated systematically for neon atomic system in the interaction with ultraintense x-ray pulses with photon energy from 937 eV to 2000 eV. A time-dependent rate equation, implemented in the detailed level accounting approximation, is utilized to study the dynamical evolution of the level population and emission properties of the highly transient plasmas. For x-ray pulses with photon energy in the range of 937-1030 eV, where 1s → 2p resonance absorption from single core-hole (SCH) states of neon charge states exist, inner-shell resonant absorption (IRA) effects play important roles in the time evolution of population and DCH spectroscopy. Such IRA physical effects are illustrated in detail by investigating the interaction of x-ray pulses at a photon energy of 944 eV, which corresponds to the 1s → 2p resonant absorption from the SCH states (1s2s 2 2p 4 , 1s2s2p 5 and 1s2p 6 ) of Ne 3+ . After averaging over the space and time distribution of the x-ray pulses, DCH spectroscopy at photon energies of 937, 944, 955, 968, 980, and 990 eV (corresponding to the 1s → 2p resonance energies of Ne 2+ -Ne 7+ , respectively) are studied in detail. The complex mechanisms of producing the DCH states are discussed, taking the DCH spectroscopy at 937 and 980 eV as examples. For photon energy larger than 1362 eV, there are no resonance absorption in the interaction, resulting in a similar physical picture of DCH spectroscopy. The dominant DCH states are due to higher ionization stages of Ne 7+ -Ne 9+ , while the DCH spectroscopy from lower charge states Ne 2+ -Ne 6+ are much weaker. With the increase of x-ray photon energy, the contributions from the lower charge states become larger.

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“…Since the electron mean free paths are obtained from the mean electron energies, for a given electron temperature listed in the table there would be electrons that need larger mean free paths to thermalize. For those situations in which substantial deviations from a Maxwell-Boltzmann distribution for the free electrons are produced, the free-electron energy distribution functions are usually obtained from a simultaneous solution of the timedependent atomic rate equations and Boltzmann electron kinetics [52]. This kind of simulation is tractable when a specific situation is simulated but not when the interest is focused on the determination of a large number of mean radiative properties in a wide range of plasma conditions.…”

Section: Theoretical and Computational Modelsmentioning

confidence: 99%

Radiative properties for astrophysical plasma mixtures in nonlocal thermodynamic equilibrium

2018

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Radiative properties play a pivotal role in astrophysical plasma flows and are needed in radiationhydrodynamic simulations in order to understand their behavior and also to interpret the plasma emission spectra, which are valuable diagnostic tools. Radiative properties of astrophysical plasma mixtures have been commonly calculated for low-density optically thin plasmas assuming coronal equilibrium and for high density assuming local thermodynamic equilibrium. However, there are wide ranges of conditions in which these thermodynamic regimes are not achieved and the plasma is in the nonlocal thermodynamic equilibrium regime. In the present work, a study of the plasma radiative properties of oxygen and iron and an astrophysical plasma mixture in nonlocal thermodynamic steady-state equilibrium is carried out. The ranges of electron temperatures and densities considered are 1-1000 eV and 10 11-10 20 cm −3 , respectively. In the study, departures from coronal and local thermodynamic equilibria in terms of the density and temperature are also analyzed. Large differences in the radiative properties that can reach two orders of magnitude when the plasma is far from these thermodynamic regimes are obtained. These analyses are done assuming the plasma to be optically thin. A brief study of the influence of the plasma self-absorption in the radiative properties of oxygen and iron is made. For that purpose, the plasma is assumed with planar geometry and the study is performed in terms of the width of the plasma slab and electron temperature and density.

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Time-dependent calculations of electron energy distribution functions for neon gas in the presence of intense XFEL radiation

Cited by 12 publications

References 27 publications

Kinetic Boltzmann approach adapted for modeling highly ionized matter created by x-ray irradiation of a solid

Kinetic Boltzmann approach adapted for modeling highly ionized matter created by x-ray irradiation of a solid

Single- and double-core-hole ion emission spectroscopy of transient neon plasmas produced by ultraintense x-ray laser pulses

Radiative properties for astrophysical plasma mixtures in nonlocal thermodynamic equilibrium

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