Experimental investigations of ion charge distributions, effective electron densities, and electron-ion cloud overlap in electron beam ion trap plasma using extreme-ultraviolet spectroscopy

G.Y. Liang, J.R.C. Lopez-Urrutia, T.M. Baumann, S.W. Epp, A. Gonchar, A. Lapierre, P.H. Mokler, M.C. Simon

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Spectra in the extreme ultraviolet range from 107 to 353 Å emitted from Fe ions in various ionization stages have been observed at the Heidelberg electron beam ion trap (EBIT) with a flat-field grating spectrometer. A series of transition lines and their intensities have been analyzed and compared with collisional-radiative simulations. The present collisional-radiative model reproduces well the relative line intensities and facilitates line identification of ions produced in the EBIT. The polarization effect on the line intensities resulting from nonthermal unidirectional electron impact was explored and found to be significant (up to 24%) for a few transition lines. Based upon the observed line intensities, relative charge state distributions (CSD) of ions were determined, which peaked at Fe23+ tailing toward lower charge states. Another simulation on ion charge distributions including the ionization and electron capture processes generated CSDs which are in general agreement with the measurements. By observing intensity ratios of specific lines from levels collisionally populated directly from the ground state and those starting from the metastable levels of Fe XXI, Fe X and other ionic states, the effective electron densities were extracted and found to depend on the ionic charge. Furthermore, it was found that the overlap of the ion cloud with the electron beam estimated from the effective electron densities strongly depends on the charge state of the ion considered, i.e. under the same EBIT conditions, higher charge ions show less expansion in the radial direction.
LanguageEnglish
Pages838-850
Number of pages12
JournalAstrophysical Journal
Volume702
Issue number2
DOIs
Publication statusPublished - 10 Sep 2009

Fingerprint

ion charge
ultraviolet spectroscopy
charge distribution
electron density
spectroscopy
electron beams
plasma
electron
ion
ions
electrons
ionization
electron capture
electron impact
simulation
distribution
gratings
spectrometers
expansion
ground state

Keywords

  • line
  • identification
  • methods
  • analytical
  • laboratory

Cite this

Liang, G.Y. ; Lopez-Urrutia, J.R.C. ; Baumann, T.M. ; Epp, S.W. ; Gonchar, A. ; Lapierre, A. ; Mokler, P.H. ; Simon, M.C. / Experimental investigations of ion charge distributions, effective electron densities, and electron-ion cloud overlap in electron beam ion trap plasma using extreme-ultraviolet spectroscopy. In: Astrophysical Journal. 2009 ; Vol. 702, No. 2. pp. 838-850.
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abstract = "Spectra in the extreme ultraviolet range from 107 to 353 {\AA} emitted from Fe ions in various ionization stages have been observed at the Heidelberg electron beam ion trap (EBIT) with a flat-field grating spectrometer. A series of transition lines and their intensities have been analyzed and compared with collisional-radiative simulations. The present collisional-radiative model reproduces well the relative line intensities and facilitates line identification of ions produced in the EBIT. The polarization effect on the line intensities resulting from nonthermal unidirectional electron impact was explored and found to be significant (up to 24{\%}) for a few transition lines. Based upon the observed line intensities, relative charge state distributions (CSD) of ions were determined, which peaked at Fe23+ tailing toward lower charge states. Another simulation on ion charge distributions including the ionization and electron capture processes generated CSDs which are in general agreement with the measurements. By observing intensity ratios of specific lines from levels collisionally populated directly from the ground state and those starting from the metastable levels of Fe XXI, Fe X and other ionic states, the effective electron densities were extracted and found to depend on the ionic charge. Furthermore, it was found that the overlap of the ion cloud with the electron beam estimated from the effective electron densities strongly depends on the charge state of the ion considered, i.e. under the same EBIT conditions, higher charge ions show less expansion in the radial direction.",
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Experimental investigations of ion charge distributions, effective electron densities, and electron-ion cloud overlap in electron beam ion trap plasma using extreme-ultraviolet spectroscopy. / Liang, G.Y.; Lopez-Urrutia, J.R.C.; Baumann, T.M.; Epp, S.W.; Gonchar, A.; Lapierre, A.; Mokler, P.H.; Simon, M.C.

In: Astrophysical Journal, Vol. 702, No. 2, 10.09.2009, p. 838-850.

Research output: Contribution to journalArticle

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T1 - Experimental investigations of ion charge distributions, effective electron densities, and electron-ion cloud overlap in electron beam ion trap plasma using extreme-ultraviolet spectroscopy

AU - Liang, G.Y.

AU - Lopez-Urrutia, J.R.C.

AU - Baumann, T.M.

AU - Epp, S.W.

AU - Gonchar, A.

AU - Lapierre, A.

AU - Mokler, P.H.

AU - Simon, M.C.

N1 - Strathprints' policy is to record up to 8 authors per publication, plus any additional authors based at the University of Strathclyde. More authors may be listed on the official publication than appear in the Strathprints' record.

PY - 2009/9/10

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N2 - Spectra in the extreme ultraviolet range from 107 to 353 Å emitted from Fe ions in various ionization stages have been observed at the Heidelberg electron beam ion trap (EBIT) with a flat-field grating spectrometer. A series of transition lines and their intensities have been analyzed and compared with collisional-radiative simulations. The present collisional-radiative model reproduces well the relative line intensities and facilitates line identification of ions produced in the EBIT. The polarization effect on the line intensities resulting from nonthermal unidirectional electron impact was explored and found to be significant (up to 24%) for a few transition lines. Based upon the observed line intensities, relative charge state distributions (CSD) of ions were determined, which peaked at Fe23+ tailing toward lower charge states. Another simulation on ion charge distributions including the ionization and electron capture processes generated CSDs which are in general agreement with the measurements. By observing intensity ratios of specific lines from levels collisionally populated directly from the ground state and those starting from the metastable levels of Fe XXI, Fe X and other ionic states, the effective electron densities were extracted and found to depend on the ionic charge. Furthermore, it was found that the overlap of the ion cloud with the electron beam estimated from the effective electron densities strongly depends on the charge state of the ion considered, i.e. under the same EBIT conditions, higher charge ions show less expansion in the radial direction.

AB - Spectra in the extreme ultraviolet range from 107 to 353 Å emitted from Fe ions in various ionization stages have been observed at the Heidelberg electron beam ion trap (EBIT) with a flat-field grating spectrometer. A series of transition lines and their intensities have been analyzed and compared with collisional-radiative simulations. The present collisional-radiative model reproduces well the relative line intensities and facilitates line identification of ions produced in the EBIT. The polarization effect on the line intensities resulting from nonthermal unidirectional electron impact was explored and found to be significant (up to 24%) for a few transition lines. Based upon the observed line intensities, relative charge state distributions (CSD) of ions were determined, which peaked at Fe23+ tailing toward lower charge states. Another simulation on ion charge distributions including the ionization and electron capture processes generated CSDs which are in general agreement with the measurements. By observing intensity ratios of specific lines from levels collisionally populated directly from the ground state and those starting from the metastable levels of Fe XXI, Fe X and other ionic states, the effective electron densities were extracted and found to depend on the ionic charge. Furthermore, it was found that the overlap of the ion cloud with the electron beam estimated from the effective electron densities strongly depends on the charge state of the ion considered, i.e. under the same EBIT conditions, higher charge ions show less expansion in the radial direction.

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KW - analytical

KW - laboratory

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