Absolute cross sections for electron-impact single ionization of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Si</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Si</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml

Djurić, N.; Bell, E W.; Guo, X. Q.; Dunn, G. H.; Phaneuf, R.A.; Bannister, M. E.; Pindzola, M. S.; Griffin, D. C.

doi:10.1103/physreva.47.4786

Cited by 24 publications

(35 citation statements)

References 25 publications

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“…For Si ii, Djurić et al (1993b) pointed out the strong role of EA through the 2p 6 3s3pnl levels. These EA transitions are significantly greater than the DI cross sections at low energies.…”

Section: The Aluminum Isoelectronic Sequencementioning

confidence: 99%

Ionization rate coefficients for the elements hydrogen through zinc

Dere

2007

A&A

155

284

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Aims. The interpretation of astrophysical spectra depends directly on a knowledge of the ionization state of the emitting plasma. This is determined, in part, from collisional ionization rate coefficients. The most recent assessments of these were performed by Arnaud & Rothenflug (1985, A&AS, 60, 425) and Arnaud & Raymond (1992, ApJ, 398, 394). Since their work, new laboratory measurements of ionization cross sections have become available as well as the Flexible Atomic Code (FAC) which enables theoretical calculations of these rates. Our goal is to provide a complete set of ionization rate coefficients for the elements hydrogen through zinc. Methods. A scaling law, which assists the analysis of ionization cross sections and rate coefficients, has been developed following the approach of Burgess & Tully (1992, A&A, 254, 436). Essentially all available measured cross sections along each isoelectronic sequence have been examined and compared to cross sections calculated with the Flexible Atomic Code (FAC) and with other calculations. Two approaches has been taken to provide a complete set of ionization cross sections. In the first, fits to scaled measured ionization cross sections, particularly for neutral and singly ionized species, are performed. In the second, fits to scaled calculated direct ionization and excitation-autoionization cross sections are performed to provide the remainder of the set. The fits to the cross sections are then integrated over a Maxwellian velocity distribution to derive ionization rate coefficients. Results. A complete set of ground level ionization cross sections and rate coefficients has been developed through the combination of these two approaches. A tabulation of parameter fits to ground level ionization rate coefficients for all atoms and ions of the elements of H through Zn is provided.

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Section: The Aluminum Isoelectronic Sequencementioning

confidence: 99%

Ionization rate coefficients for the elements hydrogen through zinc

Dere

2007

A&A

155

284

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“…For Si iii and S v the measurements of Djuric et al (1993b) and Howald et al (1986), respectively, were omitted because the measurements present clear evidence of metastable ions.…”

Section: Di: 3s Cross-sectionsmentioning

confidence: 99%

X-ray emission from thin plasmas

Urdampilleta

Kaastra

Mehdipour

2017

A&A

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Every observation of astrophysical objects involving a spectrum requires atomic data for the interpretation of line fluxes, line ratios, and ionization state of the emitting plasma. One of the processes that determines it is collisional ionization. In this study, an update of the direct ionization (DI) and excitation-autoionization (EA) processes is discussed for the H to Zn-like isoelectronic sequences. In recent years, new laboratory measurements and theoretical calculations of ionization cross-sections have become available. We provide an extension and update of previous published reviews in the literature. We include the most recent experimental measurements and fit the cross-sections of all individual shells of all ions from H to Zn. These data are described using an extension of Younger's and Mewe's formula, suitable for integration over a Maxwellian velocity distribution to derive the subshell ionization rate coefficients. These ionization rate coefficients are incorporated in the high-resolution plasma code and spectral fitting tool SPEX V3.0.

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“…Indirect processes, involving the production of intermediate excited states, also contribute to the total ionization cross section. In spite of these complications, the degree of agreement between theory and experiment today is very good [44,45], often to within 10 or 20%. Figure 9 compares the measured and calculated cross sections for the indirect and direct ionization of Scandium III(Sc 2+ ) to Scandium Sc 3+ ) [46] and the Lotz semiempirical scaling for direct ionization [48].…”

Section: Impurity Radiationmentioning

confidence: 99%

A review of recent developments in atomic processes for divertors and edge plasmas

Post

1995

Journal of Nuclear Materials

234

161

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The most promising concepts for power and particle control in tokamaks and other fusion experiments rely upon atomic processes to transfer the power and momentum from the edge plasma to the plasma chamber walls. This places a new emphasis on processes at low temperatures (1-200 eV) and high densities (10 20 -10 22 m -3 ). The most important atomic processes are impurity and hydrogen radiation, ionization, excitation, recombination, charge exchange, radiation transport, molecular collisions, and elastic scattering of atoms, molecules and ions. Important new developments have occurred in each of these areas. New calculations for impurity and hydrogen ionization, recombination, and excitation rate coefficients for low temperature plasmas that include collisional radiative effects and multi-configuration interactions indicate that earlier estimates of these rate coefficients for plasmas with low Z impurities such as beryllium are too high in selected regions of interest [1]. Transport effects and charge exchange recombination are also key elements for determining the ionization-recombination balance and radiation losses. Collisional radiative effects for hydrogen are an essential ingredient for understanding and modelling high recycling divertors [2,3]. Since the opacity in a high recycling divertor can be large for many of the strongest lines of recycling hydrogen atoms and low Z impurities, the transport of this radiation determines where the energy is deposited and strongly influences the recombination and ionization rate coefficients [4,5]. Molecular collisions play a large role in recycling and in the energy and particle Shortened PSI Review Paper 6 2 balance at the plasma edge [6]. Charge Exchange and elastic collisions are also important for determining the neutral gas pressure and the transfer of plasma energy and momentum to the chamber walls [7,8]. The best available data for these processes and an assessment of their role in plasma wall interactions are summarized, and the major areas where improved data are needed are reviewed.

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Absolute cross sections for electron-impact single ionization ofSi+andSi2+

Cited by 24 publications

References 25 publications

Ionization rate coefficients for the elements hydrogen through zinc

Ionization rate coefficients for the elements hydrogen through zinc

X-ray emission from thin plasmas

A review of recent developments in atomic processes for divertors and edge plasmas

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