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Energy-dependent excitation cross section measurements of the diagnostic lines of Fe XVII
Ist Teil von
Physical review letters, 2005-01, Vol.96
Ort / Verlag
United States
Erscheinungsjahr
2005
Quelle
APS_美国物理学会过刊
Beschreibungen/Notizen
By implementing a large-area, gain-stabilized microcalorimeter array on an electron beam ion trap, the electron-impact excitation cross sections for the dominant x-ray lines in the Fe XVII spectrum have been measured as a function of electron energy up to greater than three times the threshold energy, establishing a benchmark for atomic calculations. The results reveal a consistent overestimation by recent calculations of the excitation cross section of the resonance transition, which is shown to be at the root of several long-standing problems associated with modeling solar and astrophysical Fe XVII spectra. The data do not show strong contributions from resonance excitation contrary to recent statements in the literature.