International audienceA 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

Using the isomorphism conjectures of Baum & Connes and Farrel & Jones, we compute the algebraic K-and L-theory and the topological K-theory of cocompact planar groups (= cocompact N.E.C-groups) and of groups G appearing in an extension 1 → Z n → G → π → 1 where π is a finite group and the conjugation π-action on Z n is free outside 0 ∈ Z n . These computations apply for instance to two-dimensional crystallographic groups and cocompact Fuchsian groups.

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A model for calculating the profile of spectral lines emitted by multielectron emitters in a hot plasma is described. The Stark broadening is included in the model by using the static ion approximation and an impact approximation for the electrons. The atomic data required for the line-shape calculation are extracted from an atomic structure code and prepared as data necessary for the excited and ground levels of the radiative transition. For the cases where electron broadening is much smaller than the average ionic Stark shift, an approximation is proposed to obtain rapidly a diagonal form of the evolution operator for the emitter. Line shapes of lithiumlike and berylliumlike ions have been calculated under the conditions of recent experiments performed in laser-produced plasmas.

Stark broadening of hydrogen lines in the presence of a magnetic field is revisited, with emphasis on the role of the ion component under typical conditions of magnetized fusion devices. An impact theory for ions valid at low density ͑N e Շ 10 14 cm −3 ͒ and taking into account the Zeeman degeneracy removal of the atomic states is developed. It is shown that the Stark widths of the Lorentz triplet components strongly depend on the magnetic field. The model is validated by a computer simulation method. For the lateral components of Ly␣, we show that the impact approximation still holds for densities as high as N e ϳ 10 15 cm −3 . In contrast, for the central component as well as for the other lines from low principal quantum number, significant discrepancies between the proposed theory and the simulation results appear at high density. Application to D␣ in tokamak divertor plasma conditions shows that, in this case, the quasistatic approximation becomes more relevant.

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A computer simulation technique is used to calculate hydrogen spectral lines emitted by a plasma. These calculations are used to study ion dynamic effects on the line profiles. Results are obtained for Lyman-a, Lyman-P, and Lyman-y lines, and comparisons are made with experimental results and with other theoretical methods.

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