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Calculations of line shapes of highly excited (Rydberg) atoms and ions are important for many topics in plasma physics and astrophysics. However, the Stark broadening of the radiative transitions originating from high-n levels of hydrogen or hydrogen-like ions is rather complex, making the detailed calculations of their spectral structure very cumbersome. Here, we suggest a simple analytical method for an approximate calculation of such line shapes. The utility of the method is demonstrated in application to the line broadening in plasma, where a very good accuracy is achieved over a range of transitions, species and plasma parameters. Although the method is especially suitable for transitions with n 1, it describes rather well even first members of the spectroscopic series with n as low as 2. Accurate computer simulations are used to verify the validity of the method.

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International audienceModeling the Stark broadening of spectral lines in plasmas is a complex problem. The problem has a long history, since it plays a crucial role in the interpretation of the observed spectral lines in laboratories and astrophysical plasmas. One difficulty is the characterization of the emitter's environment. Although several models have been proposed over the years, there have been no systematic studies of the results, until now. Here, calculations from stochastic models and numerical simulations are compared for the Atoms 2014, 2 300 Lyman-α and -β lines in neutral hydrogen. Also discussed are results from the Helium-α and -β lines of Ar XVII

We study warm dense matter formed by subpicosecond laser irradiation at several 10(19) W/cm(2) of thin Ti foils using x-ray spectroscopy with high spectral (E/DeltaE approximately 15,000) and one-dimensional spatial (Deltax=13.5 microm) resolutions. Ti Kalpha doublets modeled by line-shape calculations are compared with Abel-inverted single-pulse experimental spectra and provide radial distributions of the bulk-electron temperature and the absolute-photon number Kalpha yield in the target interiors. A core with approximately 40 eV extends homogeneously up to ten times the laser-focus size. The spatial distributions of the bulk-electron temperature and Kalpha yield are strongly correlated.

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We present an analytical method for the calculation of shapes of Stark-broadened spectral lines in plasmas, applicable to hydrogen and hydrogenlike transitions (including Rydberg ones) with Δn>1. The method is based on the recently suggested quasicontiguous approximation of the static Stark line shapes, while the dynamical effects are accounted for using the frequency-fluctuation-model approach. Comparisons with accurate computer simulations show excellent agreement.

We present results for Stark broadening of high principal quantum number (up to n=15 ) Balmer lines, using an analytical (the "standard theory") approach and two independently developed computer simulation methods. The line shapes are calculated for several sets of plasma parameters, applicable to radio-frequency discharge (N(e) approximately 10(13) cm(-3)) and magnetic fusion (N(e) approximately 10(15) cm(-3)) experiments. Comparisons of the calculated line profiles to the experimental data show a very good agreement. Density and temperature dependences of the linewidths, as well as relative contributions of different Stark-broadening mechanisms, are analyzed. It is seen that the standard theory of line broadening is sufficiently accurate for the entire set of plasma conditions and spectral transitions considered here, while an alternative theory ("advanced generalized theory") is shown to be inadequate for the higher-density region. A discussion of possible reasons for this disagreement is given.