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          Institute: MPI für Kernphysik     Collection: Precision Spectroscopy and Ultracold Ensembles     Display Documents

ID: 441470.0, MPI für Kernphysik / Precision Spectroscopy and Ultracold Ensembles
Extreme-Ultraviolet Spectroscopy of Fe VI-Fe XV and its Diagnostic Application for Electron Beam Ion Trap Plasmas
Authors:Liang, G. Y.; Baumann, T. M.; Crespo López-Urrutia, J. R.; Epp, S. W.; Tawara, H.; Gonchar, A.; Mokler, P. H.; Zhao, G.; Ullrich, J.
Date of Publication (YYYY-MM-DD):2009-04-29
Title of Journal:Astrophysical Journal
Journal Abbrev.:ApJ
Issue / Number:2
Start Page:2275
End Page:2289
Copyright:© Institute of Physics and IOP Publishing Limited 2009
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Extreme-ultraviolet spectra of intermediately ionized iron ions (Fe VI-Fe XIV) in the wavelength range of 125.0-265.0 Å have been measured at the Heidelberg electron beam ion trap. Emission spectra were recorded sequentially while varying the electron energy over the range of 75-544 eV in steps of 5 eV. The observed spectra clearly show the evolution of each ionic stage as a function of the electron energy, allowing to distinguish the emission lines from neighboring ion charge species and helping to disentangle possible line blends. The collisional-radiative modeling satisfactorily reproduces the measurement. A comparison with previous astrophysical observations (Sun) reveals that some weak emissions may originate from Fe VI and Fe VII, resulting in incorrect assignment of transition lines. The calculated polarization effects due to nonthermal (monoenergetic) electrons are found to be negligible for most of the emission lines at low-energy electron impact, except for a few lines whose polarization can be over 20%. By line ratio technique, the effective electron density in the trap was estimated to be 7.1+2.4 –3.0 × 109-3.4+0.5 –0.5 × 1010 cm–3, slightly depending on the ion charge state.
Free Keywords:line: identification; methods: analytical; methods: laboratory
External Publication Status:published
Document Type:Article
Communicated by:vogt
Affiliations:MPI für Kernphysik/Group of J. Ullrich/Electron Beam Ion Trap ( J.R. Crespo Lopez-Urrutia)
External Affiliations:National Astronomical Observatories, CAS, A20 Datun Road, Chaoyang District, Beijing 100012, China
Department of Physics, University of Strathclyde, Glasgow G4 0NG, UK
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