A Green's Function Approach to the Shift of Spectral Lines in Dense Plasmas

Abstract

Variations of the spectral lines in high dense ion plasmas with temperature and pressure may be characterized by the broadening aa well as by t@ shift of spectral lines. For dense hydrogen-and alkali-plasmas (free carrier density larger than lW$3m3) one of the possible mechankms responsible for line profiles is considered to be the Coulomb interaction with free charged mrriers. Using thermodynamic Green's functions, a systematic approach to the theory of spectral lines starting from the complex dielectric function is outlined. "he line shift is derived from a perturbiltive treatment of the two-particle Green's function in the sufrounding plasma. The shift of several lines proportional to the carrier density is evaluated as a function of the temperature and compared with experimental results.Inhaltsiibersicht. Bnderungen im Linienspektrum hochdichter Ionenplasmen mit Temperatur und Druck konnen durch eine Verbreitemg sowie durch eine Verschiebung der Spektrallinien beschrieben werden. Fiir dichte Wasserstoff-und Alkaliplasmen (Dichte der freien Ladungstriiger g r o h r als 1016/cms) wird als ein moglicher Mechanismus fiir die hderung im Linienprofil die Coulombwechselwirkung mit freien Ladungstriigern betrachtet. Ein systematischer Zugang zur Theorie von Spektrallinien ausgehend von der komplexen dielektrischen Funktion und unter Verwendung thermcdynamischer Greenscher Funktionen wird benutzt. Die Linienverschiebung wird aus einer stijrungstheoretischen Behandlung der Qreenschen Funktion zweier Teilchen in einem Plasma abgeleitet. Die Verschiebung verschiedener Spektrallinien, die proportional zur Dichte der freien Ladungstriiger ist, wird in Abhiingigkeit von der Temperatur ausgewertet und mit experimentellen Werten verglichen.

Two Particle Bound States in Dense Plasmas

“…8 4 a B [24]. The calculated level shifts are comparable to those of Ropke, Seifert and Kilimann [13] received with the help of a pole approximation of the RPA dielectric function. The La-, Lp-and Ha-line shifts calculated from the energy levels are much larger than the corresponding experimental results [14] due to the fact that especially the upper levels are lowered too much.…”

Spectral Line Shapes of He I Line 3889 Å

“…The two-particle Green's function is used to calculate the line shapes. Recently, further improvements of this approach have been made by Günter et al [2], Hitzschke et al [13], and Röpke et al [63]. Optical properties of many-particle systems are described by the dielectric function ε(q, ω) based on Green's function theory, which is the response of the medium to an external electromagnetic field.…”

“…The Matsubara summation µ can be represented as a contour integral in the complex plane [67]. After performing the Matsubara frequency summation, the real and imaginary part of the diagonal electronic self-energy can be obtained [15,63,69].…”

Neutral helium spectral lines in dense plasmas

“…The perturber-radiator interaction leads to a pressure broadening (Stark broadening), which contains an electronic and an ionic contribution. Describing the ionic contribution in the quasi-static approximation by averaging over the ionic microfield [47,57,63], we get…”

“…Note that the influence of electrons and ions can be treated separately due to the difference in mass and mobility. Various approaches have been modified to account these effects [47][48][49][50][51][52]. Helium series were calculated from semiclassical approach by Griem et al [51,52], using a traditional impact approximation for electrons with cut-off procedure, while almost stationary heavy ions are treated in a quasi-static ion approximation due to static microfield.…”