Plasma pressure broadening for fewelectron emitters including strong electron collisions within a quantumstatistical theory
Abstract
To apply spectroscopy as a diagnostic tool for dense plasmas, a theoretical approach to pressure broadening is indispensable. Here, a quantumstatistical theory is used to calculate spectral line shapes of fewelectron atoms. Ionic perturbers are treated quasistatically as well as dynamically via a frequency fluctuation model. Electronic perturbers are treated in the impact approximation. Strong electronemitter collisions are consistently taken into account with an effective twoparticle Tmatrix approach. Convergent closecoupling calculations give scattering amplitudes including Debye screening for neutral emitters. For charged emitters, the effect of plasma screening is estimated. The electron densities considered reach up to ne=1027 m3. Temperatures are between T=104 and 105 K. The results are compared with a dynamically screened Born approximation for Lyman lines of H and Hlike Li as well as for the He 3889 Å line. For the last, a comprehensive comparison to simulations and experiments is given. For the H Lymana line, the width and shift are drastically reduced by the Debye screening. In the Tmatrix approach, the line shape is notably changed due to the dependence on the magnetic quantum number of the emitter, whereas the difference between spinscattering channels is negligible.
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