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P: Plasmaphysik

P 25: Dichte Plasmen 2

P 25.1: Fachvortrag

Mittwoch, 9. März 2005, 11:00–11:30, HU 3059

Dielectric and Optical Properties in Dense Plasmas — •Heidi Reinholz — Institut für Physik, Universität Rostock, 18051 Rostock

For diagnostics of plasmas, reflection, absorption and emmission as well as inverse bremsstrahlung and stopping power are used to get information about plasma parameters and scattering processes. In dense plasma, many-particle effects which are manifested as correlations and in-medium effects are relevant. A systematic approach for the theoretical description of dielectric and optical properties of dense plasmas is given within linear response theory [H. Reinholz et al., Phys. Rev. E 62 (2000) 5648]. The optical properties can be calculated via a generalized Drude formula with a dynamical collision frequency, which contains many-particle effects. Molecular dynamics simulations are used to check the validity of our results. Good agreement is found [H. Reinholz et al., Phys. Rev. E 69 (2004) 066412; A. Selchow et al., Phys.Rev. E 64 (2001) 056410] up to plasma parameters of about 2. The reflectivity on shock-compressed plasma is calculated and compared with experimental results [H. Reinholz et al., Phys. Rev. E 68 (2003) 036403]. Results for the structure factor are relevant for the diagnostics of dense plasmas as done with Thomson scattering [A. Hoell et al., Eur. J. Phys. D 29 (2004) 159]. As a further application, results for the inverse bremsstrahlung are shown. Beside the treatment of a fully ionized plasma, the formation of bound states is influencing the properties. In order to take them into account, contributions in the dielectric function are relevant. Broadening of bound states [G. Roepke et al., J. Phys. A 36 (2003) 5931] and additional scattering mechanisms are taken into account.