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Determination of the Ni XVIII plasma recombination rate coefficient.
Stockholm University, Faculty of Science, Department of Physics.
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2003 In: Astronomy & Astrophysics, ISSN 0004-6361, Vol. 409, 781- p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2003. Vol. 409, 781- p.
URN: urn:nbn:se:su:diva-25859OAI: diva2:200699
Part of urn:nbn:se:su:diva-95Available from: 2004-04-05 Created: 2004-04-05Bibliographically approved
In thesis
1. Recombination and ionization of astrophysically abundant ions
Open this publication in new window or tab >>Recombination and ionization of astrophysically abundant ions
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The electron-ion recombination and electron-impact ionization of several astrophysically abundant C, N, O, and Ni ions have been investigated using the synchrotron storage ring CRYRING. The recombination rate coefficients predominanty used in the analyses of emission line spectra and for ionization balance calculations are determined from isoelectronic fits and extrapolations of theoretical and limited experimental results available from the literature. The rate coefficients reported by various authors differ by an order of magnitude for various ion species. For low temperature plasmas(<104 K), the available information on resonant recombination rate coefficients is even more limitied and, unfortunately, most available data has been determined from LS coupling calculations, which can have adverse effects on recombination rates due to the mistreatment of autoionizing states.

For ions of C, N, and O, the production of metastable states complicates the experimental rate coefficient determinations. Some attempts have been made in this work to utilize both recombination and electron-impact ionization in estimating the metastable ion beam fractions present. Other metastable fractions have been determined by comparing the experimental recombination spectra to intermediate coupling calculations. Some of the absolute recombination rate coefficients reported in this work are given for the first time while many others vastly improve the spectral resolution of previous experiments, allowing for a more detailed study of the low energy resonances which contribute to the resonant recombination rate coefficient at low plasma electron temperatures. This increased resolution has also lead to the observation of trielectronic recombination resonances which greatly influence low temperature recombinaion rates in some ions.

Place, publisher, year, edition, pages
Stockholm: Fysikum, 2004. 60 p.
atomic data, plasma
National Category
Atom and Molecular Physics and Optics
urn:nbn:se:su:diva-95 (URN)91-7265-839-8 (ISBN)
Public defence
2004-04-26, sal FD5, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00
Available from: 2004-04-05 Created: 2004-04-05Bibliographically approved

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