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 Title: Higher-order processes in stellar opacities Author(s): Cundiff, Kirby Ray Doctoral Committee Chair(s): Lamb, Frederick K. Department / Program: Physics Discipline: Physics Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Physics, Astronomy and Astrophysics Abstract: In this thesis we calculate the influence of many-body interactions on the opacity the solar core and other non-relativistic astrophysical environments. The many-body interactions are of two basic types-multi-photon and multi-particle. Multi-photon processes of the following types are calculated: two-photon bound-bound absorption, two-photon bound-bound absorption on resonance, two-photon free-free absorption, and double Compton scattering (two photons are absorbed and one is emitted). When the electrons are in free states, higher order corrections to multi-photon interactions (free-free absorption and double Compton scattering) are found to be proportional to the temperature over the plasma frequency, $T/\omega\sb{p},$ in most astrophysical environments, where the electron energy width, $\Gamma\sb{e},$ is much smaller than the temperature, T. When the electrons are bound, the relationship is somewhat more complicated. The inverse-bremsstrahlung cross-section is calculated in a plasma using the methods of finite temperature field theory to relate it to the imaginary part of the photon self-energy. The importance of multi-particle interactions is found to be determined by the electron energy width over the temperature, $\Gamma\sb{e}/T.$ Noise of the cross-section corrections that were calculated contribute an opacity correction that is larger than two percent in any of the astrophysical environments examined (the solar core, the solar interior, and white dwarf envelopes). Issue Date: 1996 Type: Text Language: English URI: http://hdl.handle.net/2142/20145 ISBN: 9780591086782 Rights Information: Copyright 1996 Cundiff, Kirby Ray Date Available in IDEALS: 2011-05-07 Identifier in Online Catalog: AAI9702493 OCLC Identifier: (UMI)AAI9702493
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