Thermodynamic functions of a system of partially degenerate electrons and strongly coupled ions are derived from first principles. A quantum collective approach is developed to analyze nonidealities inherent to very high density plasma. The model considers the electron oscillations (plasmons) and ion oscillations (ion sound waves) as quasiparticles sharing the energy of the system. Statistical thermodynamic calculations lead to simple, analytical expressions for internal energy as well as an equation of state. A dispersion relation for the high frequency branch is introduced to take into account the partial degeneracy state and thereby to quantify temperature finiteness effect on thermodynamic properties of very dense plasma. The present results are in good quantitative agreement with the existing models and represent a significant improvement over previous calculations which are based mainly on numerical experiments. More physical insight is explicitly stated presently which makes a contribution to the theoretical knowledge of coupled degenerate plasma for thermonuclear fusion as well as of astrophysical interests.
A quantum collective approach is developed to investigate linear transport properties of a system of highly degenerate weakly coupled electrons and strongly coupled semiclassical ions. The basic formalism rests upon suitable extention of the Boltzmann–Bloch quantum transport equation. The model considers electron–ion (e–i) and electron–electron (e–e) collisions in a unified scheme of both long- and short-range Coulomb interactions. The e–e collisions contribute to the thermal conductivity calculation in the low coupling regime. Even though they can be insignificant for strongly coupled systems, the extensively used Lorentz gas approximation cannot be justified for plasmas of astrophysical interests. It is shown that the Lorentz ratio of high-density plasma may exhibit substantial negative deviation from the ideal Sommerfeld value, due to some nonidealities, such as e–e interaction and quantum effects. Results are presented under analytical and compact forms allowing numerical applications, as well as comparisons with existing theories.
Based on a quantum collective approach, electron conduction opacity is analyzed, taking into account several nonideality e †ects such as electron-electron (e-e) collisions in addition to electron-ion collisions, dynamic shielding, electron partial degeneracy, and ion coupling. The collision process is based on electron wave functions interacting with the continuum oscillations (plasma waves). The e-e collisions, the main nonideal e †ect, contribute to the thermal conductivity calculation in the intermediate coupling regime. Hence, the extensively used Lorentz gas approximation cannot be justiÐed for plasma of astrophysical interest. The present results are compared to existing theories of electron conduction in stellar matter.
An experimental analysis is conducted to visualize sidescattered second harmonic spectra originating from the critical surface of a plasma produced from a 1,064-nm laser beam. It is shown that longitudinal and transverse wave-scattering mechanisms producing the second harmonic may also alter the local plasma parameters. These irregular plasma parameter variations and the perturbed spatial uniformity of the incident laser beam can, in turn, be visualized through the second harmonic behavior. This work confirms the origin of the second harmonic production in an inhomogeneous plasma. Time evolution of the optical density of this harmonic showed spectral shifts due to the Doppler effect related to the critical surface dynamics. On the time-integrated spectra, shifted secondary peaks have been observed, indicating that the second harmonic takes its origin also from parametric decay as well as electron decay instability. Other properties of the interaction physics are deduced from the present second harmonic study.
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