Date of Award
5-2018
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Physics and Astronomy
Committee Member
Dr. Endre Takacs, Committee Chair
Committee Member
Dr. Chad Sosolik
Committee Member
Dr. Joan Marler
Committee Member
Dr. Mark Leising
Abstract
Highly charged ions have enhanced relativistic effects and compressed electronic wave functions, making their atomic transitions relevant in studies of fundamental atomic and nuclear properties. Accurate atomic data such as wavelengths, energy levels, and tran-sition probabilities are vital to the plasma communities. We report the extreme ultraviolet spectroscopy (EUV) of highly charged yttrium and xenon ions that were produced and conï¬ned with an electron beam ion trap (EBIT). The EUV spectra from these ions were recorded with a flat-ï¬eld grazing incidence grating spectrometer. In the first part of this work, new and previously observed EUV spectral lines were identified corresponding to the L-shell and a few M-shell yttrium ions (Y26+ – Y36+) in the wavelength range of 4 nm to 20 nm. The wavelength of the Li-like Y resonances, (2s - 2p1/2) and (2s - 2p3/2) and the Na-like D lines in Y, (3s - 3p1/2) and (3s - 3p3/2) were measured with an EBIT for the first time. The wavelength uncertainties of the identified transitions ranged between 0.0004 nm and 0.002 nm. Fifty nine spectral lines corresponding to ∆ n = 0 transitions within the n = 2 and n = 3 shell were identified. Line identification was assisted by the collisional-radiative non-Maxwellian code NOMAD. A few magnetic-dipole lines were measured, and the potential application of these transitions in electron density and temperature diagnostics was analyzed. In the second part of this work, we report a new method based on EUV spectroscopy of Na-like D transitions to measure the variation in mean square charge radii of Xe isotopes. The isotope shift of the Na-like D1 (3s - 3p1/2) transitions between 124Xe and 136Xe isotopes was measured and used to determine this variation by comparison with atomic structure calculations. The calculations were performed using the Relativistic Many-Body Perturba-tion (RMBPT) and Multi-Conï¬guration Dirac-Hartree-Fock (MCDHF) methods that were in excellent agreement with each other. The electron beam energy during the measurement was ï¬xed at 6 keV. The difference in the mean-square charge radii, δ < r2 > was determined to be 0.269(0.042) fm2, which agrees well with previous measurements and a recommended value reported by [AM13]. The Mg-like (3s2 - 3s3p) transitions were also employed to de-termine the differences in the mean square charge radii. Systematic studies of the measured shift were performed, providing conï¬dence in the obtained results.
Recommended Citation
Silwal, Roshani, "Extreme ultraviolet spectra of highly charged Y and Xe ions: line identification, diagnostic potential, and isotope shift" (2018). All Dissertations. 2107.
https://open.clemson.edu/all_dissertations/2107