Multiple ionization of iron by electron impact

Shah, M B; McCallion, P; Okuno, K.; Gilbody, H B

doi:10.1088/0953-4075/26/15/023

Cited by 41 publications

(42 citation statements)

References 9 publications

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“…1 we complement Seaton's comparisons with new comparisons with modern experimental data from the Queen's University of Belfast laboratory for the cases of electron impact ionization of ground state hydrogen, oxygen, magnesium and iron (Shah et al 1987;Thompson et al 1995;McCallion et al 1992;Shah et al 1993, respectively). These experimental data are in good agreement with other experiments, cover Shah et al (1987); Thompson et al (1995);McCallion et al (1992); Shah et al (1993), respectively. The plot shows the ratio of the experimental values with respect to the theoretical cross section, plotted against the collision energy E scaled by the ionization energy I.…”

Section: The Classical Drawin Formulasupporting

confidence: 92%

On inelastic hydrogen atom collisions in stellar atmospheres

Barklem

Belyaev²,

Guitou³

et al. 2011

A&A

109

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The influence of inelastic hydrogen atom collisions on non-LTE spectral line formation has been, and remains to be, a significant source of uncertainty for stellar abundance analyses, due to the difficulty in obtaining accurate data for low-energy atomic collisions either experimentally or theoretically. For lack of a better alternative, the classical "Drawin formula" is often used. Over recent decades, our understanding of these collisions has improved markedly, predominantly through a number of detailed quantum mechanical calculations. In this paper, the Drawin formula is compared with the quantum mechanical calculations both in terms of the underlying physics and the resulting rate coefficients. It is shown that the Drawin formula does not contain the essential physics behind direct excitation by H atom collisions, the important physical mechanism being quantum mechanical in character. Quantitatively, the Drawin formula compares poorly with the results of the available quantum mechanical calculations, usually significantly overestimating the collision rates by amounts that vary markedly between transitions.

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Section: The Classical Drawin Formulasupporting

confidence: 92%

On inelastic hydrogen atom collisions in stellar atmospheres

Barklem

Belyaev²,

Guitou³

et al. 2011

A&A

109

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“…2) with a maximum of 4.58 × 10 −16 cm 2 at 33 eV is in reasonable agreement with the experimental cross section obtained by Shah et al [59] (full black circles in Fig. 2; maximum of 4.08 × 10 −16 cm 2 at 35 eV).…”

Section: Eics Of Fesupporting

confidence: 91%

“…Open black squares: Experimental cross section from Freund et al [60]. Full black circles: Experimental cross section from Shah et al [59].…”

Section: Eics Of Fementioning

confidence: 99%

Electron impact ionisation cross sections of iron hydrogen clusters

et al. 2016

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Abstract.We computed electron impact ionisation cross sections (EICSs) of iron hydrogen clusters, FeHn with n = 1, 2, . . . , 10, from the ionisation threshold to 10 keV using the Deutsch-Märk (DM) and the binary-encounter-Bethe (BEB) formalisms. at 51 eV for the DM method. Cross sections calculated via the BEB method are substantially higher than the ones obtained via the DM method, up to a factor of about two for FeH and FeH2. The formation of Fe-H bonds depopulates the iron 4s orbital, causing significantly lower cross sections for the small iron hydrides compared to atomic iron. Both the DM and BEB cross sections can be fitted perfectly against a simple expression used in modelling and simulation codes in the framework of nuclear fusion research. The energetics of the iron hydrogen clusters change substantially when exact exchange is present in the density functional, while the cluster geometries do not depend on this choice.

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“…Experimental measurements of EIMI starting from Fe 0+ , including double (q f = 2), triple (q f = 3), and quadruple (q f = 4) ionization, were measured by Shah et al (1993). Double ionization of Fe 0+ was also measured earlier by Freund et al (1990).…”

Section: Application Of Fitting Formulae To Iron Ionsmentioning

confidence: 99%

Influence of Electron-Impact Multiple Ionization on Equilibrium and Dynamic Charge State Distributions: A Case Study Using Iron

Hahn

Savin

2015

ApJ

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We describe the influence of electron-impact multiple ionization (EIMI) on the ionization balance of collisionally ionized plasmas. Previous ionization balance calculations have largely neglected EIMI. Here, EIMI cross-section data are incorporated into calculations of both equilibrium and non-equilibrium charge-state distributions (CSDs). For equilibrium CSDs, we find that EIMI has only a small effect and can usually be ignored. However, for nonequilibrium plasmas the influence of EIMI can be important. In particular, we find that for plasmas in which the temperature oscillates there are significant differences in the CSD when including versus neglecting EIMI. These results have implications for modeling and spectroscopy of impulsively heated plasmas, such as nanoflare heating of the solar corona.

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Multiple ionization of iron by electron impact

Cited by 41 publications

References 9 publications

On inelastic hydrogen atom collisions in stellar atmospheres

On inelastic hydrogen atom collisions in stellar atmospheres

Electron impact ionisation cross sections of iron hydrogen clusters

Influence of Electron-Impact Multiple Ionization on Equilibrium and Dynamic Charge State Distributions: A Case Study Using Iron

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