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Electron - Ion Recombination Data for Plasma Applications: Results from Electron Beam Ion Trap and Ion Storage Ring
Stockholm University, Faculty of Science, Department of Physics. (Atomic Physics)
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis contains results of electron-ion recombination processes in atomic ions relevant for plasma applications. The measurements were performed at the Stockholm Refrigerated Electron Beam Ion Trap (R-EBIT) and at the CRYRING heavy-ion storage ring. Dielectronic recombination (DR) cross sections, resonant strengths, rate coefficients and energy peak positions in H-like and He-like S are obtained for the first time from the EBIT measurements. Furthermore, the experimentally obtained DR resonant strengths are used to check the behaviour of a scaling formula for low Z, H-and He-like iso-electronic sequences and to update the fitting parameters. KLL DR peak positions for initially He- to B-like Ar ions are obtained experimentally from the EBIT measurements. Both the results from highly charged sulfur and argon are compared with the calculations performed with a distorted wave approximation.

Absolute recombination rate coefficients of B-like C, B-like Ne and Be-like F ions are obtained for the first time with high energy resolution from storage ring measurements. The experimental results are compared with the intermediate coupling AUTOSTRUCTURE calculations. Plasma rate coefficients of each of these ions are obtained by convoluting the energy dependent recombination spectra with a Maxwell-Boltzmann energy distribution in the temperature range of 103-106 K. The resulting plasma rate coefficients are presented and compared with the calculated data available in literature.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University , 2012. , 64 p.
Keyword [en]
Highly charged ions, Atomic processes, Atomic data, Electron-ion recombination, Plasmas
National Category
Physical Sciences Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
URN: urn:nbn:se:su:diva-75311ISBN: 978-91-7447-497-8 (print)OAI: oai:DiVA.org:su-75311DiVA: diva2:515728
Public defence
2012-05-14, sal FA31, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Accepted. Paper 5: Accepted. Paper 6: Manuscript. Paper 7: Manuscript.

Available from: 2012-04-22 Created: 2012-04-14 Last updated: 2013-08-20Bibliographically approved
List of papers
1. Photo-recombination studies at R-EBIT with a Labview control and data = quisition system
Open this publication in new window or tab >>Photo-recombination studies at R-EBIT with a Labview control and data = quisition system
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2011 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 6, C01016- p.Article in journal (Refereed) Published
Abstract [en]

Equipment at the Stockholm Refrigerated Electron Beam Ion Trap (R-EBIT) was developed for photo-recombination studies. A LabView-based event mode data acquisition and R-EBIT control system was implemented. The energies of KLL dielectronic recombination resonances in Li- to C-like argon ions were determined and compared with theoretical calculations performed using a distorted wave approximation. The theoretical and experimental peak positions for Li-, Be-, and C-like argon ions agree within the error bars. For B-like argon we observe an energy shift of 9 eV between the experimentally obtained peak position and the calculated result.

Keyword
Ion sources (positive ions, negative ions, electron cyclotron = sonance (ECR), electron beam (EBIS)), X-ray detectors
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-66650 (URN)10.1088/1748-0221/6/01/C01016 (DOI)000291345600021 ()
Note
7Available from: 2011-12-20 Created: 2011-12-20 Last updated: 2017-12-08Bibliographically approved
2. The new Stockholm Electron Beam Ion Trap (S-EBIT)
Open this publication in new window or tab >>The new Stockholm Electron Beam Ion Trap (S-EBIT)
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2010 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 5, C12018- p.Article in journal (Refereed) Published
Abstract [en]

A new laboratory for highly charged ions is being built up at Stockholm University. A fully refrigerated electron beam ion trap (R-EBIT, 3 T magnet, 30 keV electron energy) was installed. It was used for spectroscopic studies, ion cooling experiments, electron ion collisions, and highly-charged ion surface studies. Here we report on an upgrade of this EBIT to a ``Super EBIT'' (S-EBIT, 4 T magnet, 260 keV electron energy). The high-voltage trapping system, the ion injection as well as the extraction scheme of S-EBIT and the LabView based operational system of S-EBIT are described.

National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-57786 (URN)10.1088/1748-0221/5/12/C12018 (DOI)
Conference
International Symposium on Electron Beam Ion Sources and Traps (EBIST), Stockholm University, April 7th - 10th, 2010
Available from: 2011-05-19 Created: 2011-05-19 Last updated: 2017-12-11Bibliographically approved
3. Electron-ion recombination of H- and He-like sulfur
Open this publication in new window or tab >>Electron-ion recombination of H- and He-like sulfur
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2011 (English)In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 44, no 22, 225203- p.Article in journal (Refereed) Published
Abstract [en]

Electron-ion recombination of sulfur ions with electrons in the energy range of 1.6-3 keV was studied at the Stockholm Refrigerated Electron Beam Ion Trap. We obtained the KLn dielectronic recombination (DR) cross sections up to n = 5 for H-like and He-like sulfur ions by observing the x-rays from the trapped ions. A fully relativistic distorted wave approximation method was used for calculating the DR cross sections, while the resonance energies were obtained with a multiconfiguration Dirac-Fock approach using the GRASP II code. The calculations agree with the experimental results within the experimental error bars. Additionally, the obtained total DR resonance strengths were used to check the behaviour of a scaling formula for low-Z, He-like iso-electronic sequence (Watanabe et al 2001 J. Phys. B: At. Mol. Opt. Phys. 34 5095).

National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-70666 (URN)10.1088/0953-4075/44/22/225203 (DOI)000296796600012 ()
Note
7Available from: 2012-01-24 Created: 2012-01-23 Last updated: 2017-12-08Bibliographically approved
4. Recombination and electron impact excitation rate coefficients for S XV AND S XVI
Open this publication in new window or tab >>Recombination and electron impact excitation rate coefficients for S XV AND S XVI
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2012 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 754, no 2, 86- p.Article in journal (Refereed) Published
Abstract [en]

Recombination and electron impact excitation of S14+ and S15+ ions was measured at the Stockholm refrigerated electron beam ion trap. The collision energy range was 1.4-3 keV, where we covered the KLL, KLM, KLN, and KLO dielectronic recombination resonances resulting in S13+ and S14+ ions. The recombination rates were obtained by detecting the charge state distribution with a newly developed time-of-flight technique. Resonance energies and cross sections calculated within the relativistic many-body perturbation theory for S15+ agree well with the experimental data. The temperature dependent rate coefficients have been extracted from the measured rates and compared with calculations from literature used for studies of collisionally ionized astrophysical plasmas. A good agreement for S15+ was obtained, while the plasma rates for S14+ were 23% lower than the so far published values. In addition to the time-of-flight spectra, the x-ray spectra, produced mainly by photo-recombination and excitation, have been also collected. The combination of these two measurements allowed us to separate the photo-recombination and the excitation spectra, and the excitation rate coefficients for summed intensities with known fractions of S14+ and S15+ ions were extracted.

Keyword
atomic data, atomic processes, plasmas
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-75369 (URN)10.1088/0004-637X/754/2/86 (DOI)000306666700007 ()
Available from: 2012-04-17 Created: 2012-04-17 Last updated: 2017-12-07Bibliographically approved
5. Electron-ion recombination rate coefficients for C II forming C I
Open this publication in new window or tab >>Electron-ion recombination rate coefficients for C II forming C I
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2012 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 753, no 2, 132- p.Article in journal (Refereed) Published
Abstract [en]

We have determined absolute dielectronic recombination rate coefficients for C II, using the CRYRING heavy-ions storage ring. The resonances due to 2s-2p (∆n = 0) core excitations are detected in the center-of-mass energy range of 0-15 eV. The experimental results are compared with intermediate coupling AUTOSTRUCTURE calculations. Plasma rate coefficients are obtained from the DR spectrum by convoluting it with a Maxwell-Boltzmann energy distribution for temperatures in the range of 103-106 K. The derived temperature dependent plasma recombination rate coefficients are presented graphically to compare with the theoretical data available in literature and parameterized by using a fit formula for convenient use in plasma modelling codes. In the temperature range of 103-2×104 K, our experimental results show that previous calculations severely underestimate the plasma rate coefficients and also our AUTOSTRUCTURE calculation does not reproduce the experimental plasma rate coefficients well. Above 2×104 K the agreement between the experimental and theoretical rate coefficients is much better, and the deviations are smaller than the estimated uncertainties.

Keyword
atomic data, atomic processes, plasmas
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-75372 (URN)10.1088/0004-637X/753/2/132 (DOI)000305912700039 ()
Available from: 2012-04-17 Created: 2012-04-17 Last updated: 2017-12-07Bibliographically approved
6. Experimental recombination rate coefficients of Be-like Frecombining into B-like F
Open this publication in new window or tab >>Experimental recombination rate coefficients of Be-like Frecombining into B-like F
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Recombination spectra of F VI forming F V have been investigated with high-energy resolution, using the CRYRING heavy-ion storage ring. The absolute recombination rate coefficients are derived in the center-of-mass energy range of 0-25 eV. The experimental results are compared with intermediate coupling AUTOSTRUCTURE calculations for 2s-2p (∆n=0) core excitation and show a very good agreement in the resonance energy positions and intensities. Trielectronic recombination with 2s2-2p2 transitions are clearly identified in the spectrum.  Metastable ion contributions are considered and found negligible. The energy dependent recombination spectra are convoluted with Maxwell-Boltzmann energy distribution in the 10-106 K temperature range. The resulting temperature dependent rate coefficients are compared with theoretical results from literature. In the 103-104 K range the calculated data significantly underestimates the plasma recombination rate coefficients. Above ~105 K, our AUTOSTRUCTURE results and plasma rate coefficients from Colgan et al. (2003) show an agreement better than 20% with the experimental results.

Keyword
atomic data, atomic processes, plasmas
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-75333 (URN)
Available from: 2012-04-16 Created: 2012-04-16 Last updated: 2012-05-03Bibliographically approved
7. RECOMBINATION RATE COEFFICIENTS OF BORON-LIKE Ne
Open this publication in new window or tab >>RECOMBINATION RATE COEFFICIENTS OF BORON-LIKE Ne
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2013 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 771, no 2, 78- p.Article in journal (Refereed) Published
Abstract [en]

Recombination of Ne5+ was measured in a merged-beam type experiment at the heavy-ion storage ring CRYRING. In the collision energy range 0-110 eV resonances due to 2s(2)2p -> 2s2p(2) (Delta n=0) and 2s(2)2p -> 2s(2)3l (Delta n=1), core excitations were observed. The experimentally derived rate coefficients agree well with the calculations obtained using AUTOSTRUCTURE. At low energies, recombination is dominated by resonances belonging to the spin-forbidden 2s2p(2)(P-4(J))nl series. The energy-dependent rate coefficients were convoluted with a Maxwell-Boltzmann electron energy distribution to obtain plasma recombination rate coefficients. The data from the literature deviate from the measured results at low temperature.

Keyword
atomic data, atomic processes, plasmas
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-92764 (URN)10.1088/0004-637X/771/2/78 (DOI)000321340700003 ()
Note

AuthorCount:7;

Available from: 2013-08-20 Created: 2013-08-20 Last updated: 2017-12-06Bibliographically approved

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Citation style
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  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
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Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
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  • text
  • asciidoc
  • rtf