A scaling of multiple ionization cross sections

Fisher, V.; Ralchenko, Yu.; Goldgirsh, A.; Fisher, D.; Maron, Y.

doi:10.1088/0953-4075/28/14/020

Cited by 62 publications

(60 citation statements)

References 33 publications

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“…The branching ratios for many ions of astrophysical interest have been given by Kaastra & Mewe (1993) and updated calculations for some systems have been given by Bautista et al (2003), Gorczyca et al (2003Gorczyca et al ( , 2006, Palmeri et al (2003), Mendoza et al (2004), and Shevelko et al (2005). For completeness, we mention that another scaling for EIMI cross sections has been given by Fisher et al (1995). This prescription consists of two formulae, one relevant at low energies, where direct processes dominate, and a second valid for high energies, which describes the total direct plus indirect cross section.…”

Section: Fitting Formulaementioning

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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Section: Fitting Formulaementioning

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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“…The corresponding cross section connecting ground states of respective ions is calculated with recommended formulas from Ref. [25].…”

Section: Collisional-radiative Modelmentioning

confidence: 99%

Accelerated recombination due to resonant deexcitation of metastable states

Ralchenko

Maron

2001

Journal of Quantitative Spectroscopy and Radiative Transfer

160

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In a recombining plasma the metastable states are known to accumulate population thereby slowing down the recombination process. We show that an account of the doubly-excited autoionizing states, formed due to collisional recombination of metastable ions, results in a significant acceleration of recombination. A fully timedependent collisional-radiative (CR) modeling for stripped ions of carbon recombining in a cold dense plasma demonstrates an order of magnitude faster recombination of He-like ions. The CR model used in calculations is discussed in detail.

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“…Multiple ionization of rare gas atoms has been studied theoretically by Becker and Faisal [30] using intense-field many-body S-matrix theory which takes into account the electron correlations and the nonperturbative field interactions. The recollision electron impact ionization cross sections used in the calculations are determined from the Lotz formula [31] and the empirical formulations of Fisher et al [32]. These results, integrated over experimental volumes, are in good agreement with a large number of experimental investigations once normalized to the experimental saturation intensity.…”

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confidence: 52%

Suppression of Multiple Ionization of Atomic Ions in Intense Ultrafast Laser Pulses

Greenwood

Johnston²,

McKenna³

et al. 2002

Phys. Rev. Lett.

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The interaction of an intense laser field with a beam of atomic ions has been investigated experimentally for the first time. The ionization dynamics of Ar 1 ions and Ar neutrals in a 60 fs, 790 nm laser pulse have been compared and contrasted at intensities up to 10 16 W cm 22 . Our results show that nonsequential ionization from an Ar 1 target is strongly suppressed compared with that from the corresponding neutral target. We have also observed for the first time the strong field ionization of high lying target metastable levels in the Ar 1 beam. DOI: 10.1103/PhysRevLett.88.233001 PACS numbers: 32.80.Fb There is considerable current interest in the interaction of high intensity ͑10 13 10 18 W cm 22 ͒ radiation with dilute matter, where the external electric field strength becomes comparable to molecular bond and valance electron binding strengths. Studies have been carried out with targets of atoms, molecules, clusters [1], and most recently molecular ions [2,3], in order to elucidate the new physics observable in this highly nonlinear regime. These include the study of high harmonic generation [4], strong field effects in molecular dissociation, and the enhancement of multiple ionization in atoms [5,6]. Work is currently underway to generate attosecond pulses through harmonic generation [7,8], and coherent x-ray generation could be possible for highly charged ions in the presence of superintense fields [9,10].Both experiment and theory have shown that, in femtosecond laser pulses, multiple ionization of atoms is enhanced by nonsequential processes [5,6,11,12]. The physical model which best describes the observed behavior is known as the "atomic antenna" [13] or "recollision" [14,15] model. In this picture the first electron is removed from the atom by tunneling through the barrier created by interaction of the external field with the atomic potential. This electron is then accelerated in the external field and, depending on the initial phase, can return to the singly charged ion with energies up to 3.17U P [6], where U P is the classical ponderomotive energy in the field. Multiple ionization is thus via electron interaction with the ionic core. Evidence for this mechanism includes large reductions in nonsequential ionization rates for circularly polarized fields and more recently from the momentum distribution of the recoil ions [16,17], and coincidence measurements between ions and ejected electrons [18]. However, it has proved difficult to predict quantitative yields for the product ions without using large-scale calculations through the S-matrix approach [19] or by obtaining a time-dependent solution of the Schrödinger equation [20].By including the effects of excitation from the recollision followed by tunneling [21] and taking into account the Coulomb focusing on the active electron [22], better agreement with experiment has been obtained. The importance of multiple returns to the core has been demonstrated experimentally by a reduction in nonsequential ionization when few cycle pulses are used [23]....

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A scaling of multiple ionization cross sections

Abstract: On the basis of average experimental data we demonstrate scaling laws of electron-impact multiple ionization cross sections and propose expressions for the cross sections for arbitrary atoms and ions.

Cited by 62 publications

References 33 publications

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

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

Accelerated recombination due to resonant deexcitation of metastable states

Suppression of Multiple Ionization of Atomic Ions in Intense Ultrafast Laser Pulses

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