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Title: NON-EQUILIBRIUM MODELING OF THE FE XVII 3C/3D LINE RATIO IN AN INTENSE X-RAY FREE-ELECTRON LASER EXCITED PLASMA

Abstract

Recent measurements using an X-ray Free Electron Laser (XFEL) and an Electron Beam Ion Trap at the Linac Coherent Light Source facility highlighted large discrepancies between the observed and theoretical values for the Fe xvii 3C/3D line intensity ratio. This result raised the question of whether the theoretical oscillator strengths may be significantly in error, due to insufficiencies in the atomic structure calculations. We present time-dependent spectral modeling of this experiment and show that non-equilibrium effects can dramatically reduce the predicted 3C/3D line intensity ratio, compared with that obtained by simply taking the ratio of oscillator strengths. Once these non-equilibrium effects are accounted for, the measured line intensity ratio can be used to determine a revised value for the 3C/3D oscillator strength ratio, giving a range from 3.0 to 3.5. We also provide a framework to narrow this range further, if more precise information about the pulse parameters can be determined. We discuss the implications of the new results for the use of Fe xvii spectral features as astrophysical diagnostics and investigate the importance of time-dependent effects in interpreting XFEL-excited plasmas.

Authors:
; ; ;  [1];  [2]
  1. Auburn University, Auburn, AL 36849 (United States)
  2. Los Alamos National Laboratory, MS F663, Los Alamos, NM 87545 (United States)
Publication Date:
OSTI Identifier:
22518814
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 801; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; COMPARATIVE EVALUATIONS; ELECTRON BEAMS; EQUILIBRIUM; FREE ELECTRON LASERS; IRON IONS; LIGHT SOURCES; MULTICHARGED IONS; OSCILLATOR STRENGTHS; PLASMA; TIME DEPENDENCE; TRAPS; X RADIATION

Citation Formats

Loch, S. D., Ballance, C. P., Li, Y., Fogle, M., and Fontes, C. J., E-mail: loch@physics.auburn.edu. NON-EQUILIBRIUM MODELING OF THE FE XVII 3C/3D LINE RATIO IN AN INTENSE X-RAY FREE-ELECTRON LASER EXCITED PLASMA. United States: N. p., 2015. Web. doi:10.1088/2041-8205/801/1/L13.
Loch, S. D., Ballance, C. P., Li, Y., Fogle, M., & Fontes, C. J., E-mail: loch@physics.auburn.edu. NON-EQUILIBRIUM MODELING OF THE FE XVII 3C/3D LINE RATIO IN AN INTENSE X-RAY FREE-ELECTRON LASER EXCITED PLASMA. United States. doi:10.1088/2041-8205/801/1/L13.
Loch, S. D., Ballance, C. P., Li, Y., Fogle, M., and Fontes, C. J., E-mail: loch@physics.auburn.edu. Sun . "NON-EQUILIBRIUM MODELING OF THE FE XVII 3C/3D LINE RATIO IN AN INTENSE X-RAY FREE-ELECTRON LASER EXCITED PLASMA". United States. doi:10.1088/2041-8205/801/1/L13.
@article{osti_22518814,
title = {NON-EQUILIBRIUM MODELING OF THE FE XVII 3C/3D LINE RATIO IN AN INTENSE X-RAY FREE-ELECTRON LASER EXCITED PLASMA},
author = {Loch, S. D. and Ballance, C. P. and Li, Y. and Fogle, M. and Fontes, C. J., E-mail: loch@physics.auburn.edu},
abstractNote = {Recent measurements using an X-ray Free Electron Laser (XFEL) and an Electron Beam Ion Trap at the Linac Coherent Light Source facility highlighted large discrepancies between the observed and theoretical values for the Fe xvii 3C/3D line intensity ratio. This result raised the question of whether the theoretical oscillator strengths may be significantly in error, due to insufficiencies in the atomic structure calculations. We present time-dependent spectral modeling of this experiment and show that non-equilibrium effects can dramatically reduce the predicted 3C/3D line intensity ratio, compared with that obtained by simply taking the ratio of oscillator strengths. Once these non-equilibrium effects are accounted for, the measured line intensity ratio can be used to determine a revised value for the 3C/3D oscillator strength ratio, giving a range from 3.0 to 3.5. We also provide a framework to narrow this range further, if more precise information about the pulse parameters can be determined. We discuss the implications of the new results for the use of Fe xvii spectral features as astrophysical diagnostics and investigate the importance of time-dependent effects in interpreting XFEL-excited plasmas.},
doi = {10.1088/2041-8205/801/1/L13},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 801,
place = {United States},
year = {Sun Mar 01 00:00:00 EST 2015},
month = {Sun Mar 01 00:00:00 EST 2015}
}