1. Evaluation of Fe XIV Intensity Ratio for Electron Density Diagnostics by Laboratory Measurements
- Author
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Tomoko Kawate, Izumi Murakami, Nagaaki Kambara, Daiji Kato, Yasuko Kawamoto, Hiroyuki A. Sakaue, Hirohisa Hara, Tetsutarou Oishi, and Nobuyuki Nakamura
- Subjects
Nuclear and High Energy Physics ,Electron density ,Materials science ,EBIT ,ionized gas ,Plasma ,Electron ,QC770-798 ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Ion ,Large Helical Device ,Ionization ,Excited state ,Nuclear and particle physics. Atomic energy. Radioactivity ,Atomic physics ,collisional–radiative model ,LHD ,EUV spectroscopy ,Electron beam ion trap ,electron density diagnostics - Abstract
The intensity ratio of Fe XIV 264.765A/274.203A is useful to determine the electron density of solar corona, and the relationship between the electron density and the intensity ratio obtained from a model should be evaluated using laboratory plasmas to estimate the electron density more precisely. We constructed a new collisional–radiative model (CR-model) for Fe XIV (an Al-like iron ion) by considering the processes of proton-impact excitation and electron-impact ionization to the excited states of a Mg-like iron ion. The atomic data used in the CR-model were calculated using the HULLAC atomic code. The model was evaluated based on laboratory experiments using a compact electron beam ion trap, called CoBIT, and the Large Helical Device (LHD). The measured Fe XIV 264.785 Å/274.203 Å line intensity ratio with CoBIT was 1.869 ± 0.036, and it agreed well with our CR-model results. Concurrently, the measured ratio using LHD was larger than the results of our CR-model and CHIANTI. The estimated electron densities using our CR-model agreed with those from CHIANTI within a factor of 1.6–2.4 in the range of ne≈1010−11cm−3. Further model development is needed to explain the ratio in a high-electron density region.
- Published
- 2021