Frequency-fluctuation model for line-shape calculations in plasma spectroscopy
- Departement de Physique de Interactions Ioniques et Moleculaires, Case 232, Universite de Provence, Centre de Saint Jerome, 13397 Marseille cedex 20 (France)
- L-58 Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (United States)
- Center for the Study of Terrestrial and Extraterrestrial Atmospheres, Department of Physics and Astronomy, Howard University, Washington, D.C. 20059 (United States)
A model is developed that permits the calculation of the radiation emitted by complex or highly charged ions in a plasma. The model is based on the usual separation of the plasma-emitter interaction into the homogeneous broadening effects of the fast electrons and the inhomogeneous broadening arising from slow ions. For plasma conditions where the ion motion can be neglected, the spectrum is the usual static line shape. To account for ion dynamics, the frequency-fluctuation model is introduced by decomposing the line shape of each radiative transition into a sum of radiative channels that are associated with the smallest observable inhomogeneities that form the static profile. The fluctuations of the ion microfield, the ion dynamics effect, is modeled by an exchange process between the static radiative channels. This results in both a smoothing and an overall coalescence of the radiative channels and depends strongly on an averaged characteristic fluctuation rate associated with the dynamics of the interaction of the local plasma microfield with the ion. This rate is formally related to the double-time field-field correlation function behavior. This stochastic model of the observed frequency fluctuations permits fast and accurate calculations of the emitted spectral profiles, including ion dynamics emitted by complex ions in a wide range of plasma conditions.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6448629
- Journal Information:
- Physical Review A; (United States), Vol. 51:3; ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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