Dielectronic recombination data for dynamic finite-density plasmas - XIII. The magnesium isoelectronic sequence
ABSTRACT We have calculated total and partial final- state level- resolved dielectronic recombination ( DR) rate coe. cients for the ground and metastable initial levels of 21 Mg- like ions between Al+ and Xe42+. This is the final part of the assembly of a levelresolved DR database necessary for modelling dynamic finite-density plasmas within the generalized collisional-radiative framework. Calculations have been performed in both LS-and intermediate coupling, allowing for. n = 0 and. n = 1 core- excitations from ground and metastable levels. Complementary partial and total radiative recombination RR coeficients have been calculated for the same ions viz. Al+ through Zn18+, as well as Kr24+, Mo30+, and Xe42+. Fitting coeficients which describe the total RR and DR rate coeficients (separately) are also presented here. Results for a selection of ions fromthis sequence are discussed, and compared with existing theoretical and experimental results. A full set of results can be accessed from the Atomic Data and Analysis Structure (ADAS) database or from the Oak Ridge Controlled Fusion Atomic Data Center (http://www-cfadc.phy.ornl.gov/data_and_codes). The complexity of further M-shell sequences, both from the atomic and modelling perspectives, renders this juncture a natural conclusion for the assemblage of the partial database. Further M-shell work, has and will, focus more on total rate coe. cients, rather than partials, at least in the medium term.
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ABSTRACT: Results for electron–ion recombination and photoionization of , with emphasis in high-temperature region, are presented from ab initio unified method. The unified method, based on close coupling (CC) approximation and R-matrix method, (i) subsumes both the radiative recombination (RR) and dielectronic recombination (DR), (ii) enables self-consistent sets of photoionization and recombination cross sections from using an identical wavefunction for both the processes, and (iii) provides state-specific recombination rates of a large number of bound states. A large CC wavefunction expansion, which includes the ground and 28 core excitations of n=2 and 3 complexes and span a wide energy range, has been used. Compared to Δn=2–2, Δn=2–3 core excitations are found to introduce strong resonant structures and enhance the background photoionization cross sections (σPI) in the high-energy region. These features along with prominent photoexcitation-of-core (PEC) resonances at n=3 core thresholds have increased the unified total recombination rate coefficients (αR(T)) at temperatures , region of maximum abundance of the ion in collisional equilibrium, by a factor of 1.6 over previous calculations. State-specific recombination rate coefficients αR(nLS), which include both the RR and DR, are presented for the first time for 685 bound states with n⩽10 and l⩽9. The unified total recombination rate with photoelectron energy αR(E) is presented and the role of low-energy near-threshold fine structure resonances is illustrated. The present results should provide a reasonably complete self-consistent set of recombination rates and photoionization cross sections for astrophysical modelings of high-temperature plasmas from optical to far-ultraviolet wavelength regions.Journal of Quantitative Spectroscopy and Radiative Transfer 11/2008; DOI:10.1016/j.jqsrt.2008.07.007 · 2.29 Impact Factor
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ABSTRACT: New data for the calculation of ionization and recombination rates have been published in the past few years, most of which are included in the CHIANTI database. We used these data to calculate collisional ionization and recombination rates for the non-Maxwellian κ-distributions with an enhanced number of particles in the high-energy tail, which have been detected in the solar transition region and the solar wind. Ionization equilibria for elements H to Zn are derived. The κ-distributions significantly influence both the ionization and recombination rates and widen the ion abundance peaks. In comparison with the Maxwellian distribution, the ion abundance peaks can also be shifted to lower or higher temperatures. The updated ionization equilibrium calculations result in large changes for several ions, notably Fe VIII-Fe XIV. The results are supplied in electronic form compatible with the CHIANTI database.The Astrophysical Journal Supplement Series 05/2013; 206(1):6. DOI:10.1088/0067-0049/206/1/6 · 14.14 Impact Factor
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ABSTRACT: Several laboratory facilities were used to benchmark theoretical spectral models those extensively used by astronomical communities. However there are still many differences between astrophysical environments and laboratory miniatures that can be archived. Here we setup a spectral analysis system for astrophysical and laboratory (SASAL) plasmas to make a bridge between them, and investigate the effects from non-thermal electrons, contribution from metastable level-population on level populations and charge stage distribution for coronal-like, photoionized, and geocoronal plasmas. Test applications to laboratory measurement (i.e. EBIT plasma) and astrophysical observation (i.e. Comet, Cygnus X-3) are presented. Time evolution of charge stage and level population are also explored for collisional and photoionized plasmas.The Astrophysical Journal 01/2014; 783(2). DOI:10.1088/0004-637X/783/2/124 · 6.28 Impact Factor