Jiaolong Zeng

STATISTICAL EQUILIBRIUM OF COPPER IN THE SOLAR ATMOSPHERE

Non-local thermodynamic equilibrium (NLTE) line formation for neutral copper in the one-dimensional solar atmospheres is presented for the atomic model, including 96 terms of Cui and the ground state of Cuii .T he accurate oscillator strengths for all the line transitions in model atom and photoionization cross sections were calculated using the R-matrix method in the Russell–Saunders coupling scheme. The main NLTE mechanism for Cui is the ultraviolet overionization. We find that NLTE leads to systematically depleted total absorption in the Cui lines and, accordingly, positive abundance corrections. Inelastic collisions with neutral hydrogen atoms produce minor effects on the statistical equilibrium of Cui in the solar atmosphere. For the solar Cui lines, the departures from LTE are found to be small, the mean NLTE abundance correction of ∼0.01 dex. It was found that the six low-excitation lines, with excitation energy of the lower level Eexc 1.64 eV, give a 0.14 dex lower mean solar abundance compared to that from the six Eexc > 3.7 eV lines, when applying experimental gf -values of Kock & Richter. Without the two strong resonance transitions, the solar mean NLTE abundance from 10 lines of Cui is log e� (Cu) = 4.19 ± 0.10, which is consistent within the error bars with the meteoritic value 4.25 ± 0.05 of Lodders et al. The discrepancy between Eexc = 1.39–1.64 eV and Eexc > 3.7 eV lines can be removed when the calculated gf -values are adopted and a mean solar abundance of log e� (Cu) = 4.24 ± 0.08 is derived.

Complete Auger decay pathways of Kr 3d?1 hole levels including direct double processes

The detailed level-to-level single and double Auger decay rates of Kr 3d−1 hole states are investigated in the framework of the first and second perturbation theory implemented by distorted wave approximation with the balanced large-scale configuration interaction of the successive ions being taken into account. The branching ratios of cascade and direct double Auger decay to the total probability are predicted to be 16.5% and 16.1%, respectively, for Kr and 16.8% and 17.2% for Kr , resulting in total double branching ratios of 32.6% and 34.0% for the two levels of Kr 3d−1 hole. A comparison is made with the available experimental results on the branching ratio into triply charged ions and good agreement was found with the most recent published work. This work represents the first theoretical study to correctly explain the experimental measurements. The complete pathways were depicted by including the direct double Auger decay process. Compared with the Auger decay of Ar 2p−1, the fraction of the cascade double of Kr 3d−1 is dramatically enhanced yet that of direct double Auger processes is only slightly increased.

Detailed level accounting investigation on the radiative opacity of gold plasmas at high temperatures

The energy levels, oscillator strengths, photoionization cross sections and parameters to determine the line widths have been obtained for highly ionized gold ions ranging from Au60+ to Au78+. Using the database built from these atomic data, a fully relativistic detailed level accounting (DLA) model is developed to calculate spectrally resolved and Rosseland and Planck mean opacities of gold plasmas at high temperatures in local thermodynamic equilibrium. The main physical effects have been considered to obtain as accurate radiative opacity as possible. As illustrative examples, detailed results are given for gold plasmas at three iso-thermal sequences of 1500, 2500 and 5000 eV with mass densities being 0.005, 0.05 and 0.5 g cm−3, respectively, to show the general characteristics of gold plasmas at high temperatures. The radiative opacity has also been obtained by using an average atom model and the results are compared with those of the DLA formalism.

Nuclear quantum dynamics in dense hydrogen

Nuclear dynamics in dense hydrogen, which is determined by the key physics of large-angle scattering or many-body collisions between particles, is crucial for the dynamics of planets evolution and hydrodynamical processes in inertial confinement confusion. Here, using improved ab initio path-integral molecular dynamics simulations, we investigated the nuclear quantum dynamics regarding transport behaviors of dense hydrogen up to the temperatures of 1 eV. With the inclusion of nuclear quantum effects (NQEs), the ionic diffusions are largely higher than the classical treatment by the magnitude from 20% to 146% as the temperature is decreased from 1 eV to 0.3 eV at 10 g/cm3, meanwhile, electrical and thermal conductivities are significantly lowered. In particular, the ionic diffusion is found much larger than that without NQEs even when both the ionic distributions are the same at 1 eV. The significant quantum delocalization of ions introduces remarkably different scattering cross section between protons compared with classical particle treatments, which explains the large difference of transport properties induced by NQEs. The Stokes-Einstein relation, Wiedemann-Franz law, and isotope effects are re-examined, showing different behaviors in nuclear quantum dynamics.Nuclear quantum effects (NQEs) on the structures and transport properties of dense liquid hydrogen at densities of 10-100 g/cm3 and temperatures of 0.1-1 eV are fully assessed using \textit{ab initio} path-integral molecular dynamics simulations. With the inclusion of NQEs, ionic diffusions are strongly enhanced by the magnitude from 100% to 15% with increasing temperature, while electrical conductivities are significantly suppressed. The analyses of ionic structures and zero-point energy show also the importance of NQEs in these regime. The significant quantum delocalization of ions introduces expressively different scattering cross section between protons compared with classical particle treatments, which can explain the large alterability of transport behaviors. Furthermore, the energy, pressure, and isotope effects are also greatly influenced by NQEs. The complex behaviors show that NQEs can not be neglected for dense hydrogen even in the warm dense regime.

Population kinetics and M band emission spectra of gold plasmas in non-local thermodynamic equilibrium by using a detailed relativistic configuration approach

A collisional-radiative model based on the approach of detailed relativistic configurations is developed, where the complete set of atomic data including photo-excitation, photoionization, electron impact excitation, electron impact ionization and autoionization is calculated, and the data of the inverse processes are obtained by detailed balance. The population distribution is obtained by solving the rate equation under the steady-state condition. The present model is applied to calculate the charge state distribution and M band emission spectra of gold plasmas in non-local thermodynamic equilibrium under a variety of plasma conditions. Comparisons between the present work and experimental results were made and good agreement is found. For the strong transition lines, the intensities predicted by the present model agree with those of experimental spectra within 50%. The present work is useful in analyzing and interpreting experiments as well as in diagnosing the electron temperature in experiments.

RADIATIVE OPACITY OF IRON STUDIED USING A DETAILED LEVEL ACCOUNTING MODEL

The opacity of iron plasma in local thermodynamic equilibrium is studied using an independently developed detailed level accounting model. Atomic data are generated by solving the full relativistic Dirac-Fock equations. State mixing within one electronic configuration is considered to include part of the correlations between electrons without configuration interaction matrices that are too large being involved. Simulations are carried out and compared with several recent experimental transmission spectra in the M- and L-shell absorption regions to reveal the high accuracy of the model. The present model is also compared with the OPAL, LEDCOP and OP models for two isothermal series at T = 20 eV and T = 19.3 eV. It is found that our model is in good agreement with OPAL and LEDCOP while it has discrepancies with OP at high densities. Systematic Rosseland and Planck mean opacities in the range 10-1000 eV for temperature and 10–5-10–1 g cm–3 for density are also presented and compared with LEDCOP results, finding good agreement at lower temperatures but apparent differences at high temperatures where the L- and K-shell absorptions are dominant.

The influence of core–valence electron correlations on the convergence of energy levels and oscillator strengths of ions with an open 3d shell using Fe VIII as an example

Accurate atomic data, such as fine structure energy levels and oscillator strengths of different ionization stages of iron ions, are important for astrophysical and laboratory plasmas. However, some important existing oscillator strengths for ions with an open 3d shell found in the literature might not be accurate enough for practical applications. As an example, the present paper checks the convergence behaviour of the energy levels and oscillator strengths of Fe VIII by systematically increasing the 3pn–3dn (n = 1, 2, 3 and 6) core–valence electron correlations using the multiconfiguration Hartree–Fock method. The results show that one should at least include up to 3p3–3d3 core–valence electron correlations to obtain converged results. Large differences are found between the present oscillator strengths and other theoretical results in the literature for some strong transitions.

Photoionization of O III low-lying states: autoionization resonance energies and widths of some 1s-2p excited states

Twenty-four-state close-coupling calculations are performed on the inner-shell photoionization of the terms belonging to the configurations 2s22p2 and 2s2p3 of the O III ion. The resonance energies and widths of the transitions of a 1s electron excited into the 2p orbital are determined by analysing the resonance structures of the photoionization cross sections. The calculations show that the autoionization resonance widths of these inner-shell transitions are larger than the corresponding Doppler full width at half maximum (FWHM) and Stark FWHM by a factor of two or three under typical plasma conditions (such as a temperature of 10 eV and a density of 0.0016 g cm-3). The autoionization resonance broadening is obviously the main broadening mechanism and should be considered when analysing the plasma spectrum. Only when the electron density is larger than 5×1021 cm-3 may the Stark FWHM be larger than the autoionization resonance FWHM.

Relativistic effects on the cross section and circular polarization of x-ray radiation following longitudinally-polarized electron impact excitation of highly charged ions

Detailed calculations using a fully relativistic distorted-wave method are carried out for the cross sections of longitudinally polarized electron impact excitation from the ground state to the magnetic sublevels of the 1s2p state of highly charged He-like ions. The relativistic effects on the cross sections and circular polarization of the x-ray photoemission are investigated in detail. For the excitation process, results show that the relativistic effects may become important leading to considerable enhancements in the cross sections. The inclusion of the relativistic effects can modify the cross sections by several orders of magnitude, especially to the Mf = and magnetic sublevels. For the de-excitation process, the relativistic effects make the degree of circular polarization decreases, these features are more pronounced when the incident electron energy and/or atomic number increase. The relativistic effects are found to be much larger compared to the case of the linear polarization of radiation.

Auger energies, branching ratios, widths and x-ray rates of double K-vacancy states of Ne2 +: a close-coupling calculation

A close-coupling calculation is performed for the photoionization cross section of the high-lying core-excited state 1s2s 2 2p 51 P o of Ne 2+ in the energy region of the double K-vacancy resonance 1s 0 2s 2 2p 61 S. The calculation is carried out by using the R-matrix method in the LS-coupling scheme, which includes 27 target states and extensive configuration interaction. The KK−KL x-ray energy, rate and autoionization width of the double K-vacancy state, together with KK−KLL Auger energies and branching ratios of the main channels, are obtained from the cross sections and the contributions of these channels. The calculated resonance energy and x-ray rate are in good agreement with the existing experimental and theoretical results. For the Auger width, our result agrees well with the available experimental result and it is very close to the average of other theoretical data, which shows considerable differences with each other. The Auger energy of the predominate channel KK−KL23L23 2 Di s in rather good agreement with recent experiments on the Auger spectra. Our branching ratios for the channels KK−KL23L23 2 D and KK−KL23L23 2 S are larger than the results obtained by the multi-configuration Dirac–Fock method by ∼20% on average, which may be due to the coupling of the continuum channels.