A study of diagnostic x-ray lines in heliumlike neon using an electron beam ion trap

Thesis/Dissertation · Fri Oct 01 00:00:00 EDT 1993

DOI:https://doi.org/10.2172/10142436· OSTI ID:10142436

Wargelin, Bradford John ^[1]

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1. Univ. of California, Berkeley, CA (United States)

Heliumlike ions play an extremely important role in X-ray astrophysics because of their emissivity and because the relative intensities of their emission lines can be used to infer physical characteristics of X-ray emitting plasmas, including temperature, electron density, and ionization balance. In order to properly apply these diagnostics, accurate atomic data are required, including cross sections for collisional excitation and ionization, radiative rates, and the wavelengths and strengths of satellite lines. Although theoretical atomic models have been created to estimate many of the rates and cross sections involved, very few experimental results are available for comparison with theoretical predictions. This thesis describes an experimental study of heliumlike neon using an electron beam ion trap, a device specifically designed to study X-ray emission from highly charged ions. Using a low-energy X-ray spectrometer designed and built for this experiment, electron impact excitation cross sections and dielectronic satellite strengths were measured for all significant n = 2→1 emission lines in He-like and Li-like Ne over a range of energy extending from well below the direct excitation threshold of the lines to over fourteen times the threshold energy. The cross section for innershell ionization of Li-like Ne, which excites the He-like forbidden line, was also measured. In addition, the radiative and collisional depopulation rates of the metastable ls2s ³S₁, state, which form the basis of the He-like Ne density diagnostic, were determined. Experimental results were generally in agreement with theoretical predictions, although some significant differences were noted, particularly for the wavelengths and resonance strengths of dielectronic satellites.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 10142436
• Report Number(s): UCRL-LR-115961; ON: DE94009372
• Resource Relation: Other Information: TH: Thesis (Ph.D.); PBD: Oct 1993
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
NEON IONS
X-RAY SPECTRA
ELECTRON BEAM ION SOURCES
PLASMA DIAGNOSTICS
IONIZATION
MULTICHARGED IONS
X-RAY SPECTROSCOPY
LIFETIME
ASTROPHYSICS
EXCITATION
664200
664400
661300
700380
SPECTRA OF ATOMS AND MOLECULES AND THEIR INTERACTIONS WITH PHOTONS
EXPERIMENTALLY DERIVED INFORMATION ON ATOMIC AND MOLECULAR PROPERTIES
OTHER ASPECTS OF PHYSICAL SCIENCE
ELEMENTARY AND CLASSICAL PROCESSES IN PLASMAS