arXiv subjects

August Wierling

Publications and source records attributed to August Wierling.

4 recordsLinked to original sources

arXiv2009

Fitting the dielectric response of collisionless plasmas by continued fractions

We present an approximation scheme for the dielectric response of thermal collisionless plasmas at arbitrary degeneracy. A T-fraction representation is obtained from the known expansions of the real part of the dielectric function for small and large arguments. The partial numerators and denominators of the continued fraction are generated by a modified Q-D algorithm. For several typical values of the degeneracy parameter $θ$, extensive tables for the expansion coefficients and the partial numerators and denominations are given allowing for an easy implementation of the fitting function. Also, an error analysis is performed.

physics.plasm-ph↗

arXiv2009

The influence of local field corrections on Thomson scattering in non-ideal two-component plasmas

Thomson scattering in non-ideal (collision-dominated) two-component plasmas is calculated accounting for electron-ion collisions as well as electron-electron correlations. This is achieved by using a novel interpolation scheme for the electron-electron response function generalizing the traditional Mermin approach. Also, ions are treated as randomly distributed inert scattering centers. The collision frequency is taken as a dynamic and complex quantity and is calculated from a microscopic quantum-statistical approach. Implications due to different approximations for the electron-electron correlation, i.e. different forms of the OCP local field correction, are discussed.

physics.plasm-ph↗

arXiv2008

Interpolation between static local field corrections and the Drude model by a generalized Mermin approach

In non-ideal plasmas, the dielectric function has to be treated beyond the random phase approximation. Correlations and well as collisions have to be included. These corrections are known as (dynamical) local field corrections. With the help of the Zubarev approach to linear response theory, a relaxation time approximation is proposed leading to an interpolation scheme between static local field corrections and the Drude model in the long wave length limit. The approach generalizes the Mermin approximation for the dielectric function and allows for the inclusion of a dynamical collision frequency. Exploratory calculations for a classical two-component plasma at intermediate coupling are presented.

physics.plasm-ph↗

arXiv2006

Optical properties and one-particle spectral function in non-ideal plasmas

A basic concept to calculate physical features of non-ideal plasmas, such as optical properties, is the spectral function which is linked to the self-energy. We calculate the spectral function for a non-relativistic hydrogen plasma in $GW$-approximation. In order to go beyond $GW$ approximation, we include self-energy and vertex correction to the polarization function in lowest order. Partial compensation is observed. The relation of our approach to $GW$ and $GWΓ$ calculations in other fields, such as the band-structure calculations in semiconductor physics, is discussed. From the spectral function we derive the absorption coefficient due to inverse bremsstrahlung via the polarization function. As a result, a significant reduction of the absorption as compared to the Bethe-Heitler formula for bremsstrahlung is obtained.

physics.plasm-ph↗