96 research outputs found
Thermodynamic coherence of the Variational Average-Atom in Quantum Plasmas (VAAQP) approach
A new code called VAAQP (Variational Average-Atom in Quantum Plasmas) is
reported. The model as well as main results of previous studies are briefly
recalled. The code is based on a new fully variational model of dense plasmas
at equilibrium with quantum treatment of all electrons. The code can calculate
the Average Atom structure and the mean ionization from the variational
equations respecting the virial theorem and without imposing the neutrality of
the Wigner-Seitz sphere. The formula obtained for the electronic pressure is
simple and does not require any numerical differentiation. A description of the
principal features of the code is given. The thermodynamic consistency of the
results obtained with VAAQP is shown by a comparison with another approach on
the example of the aluminium 10 eV isotherm EOS curve. A first comparison to an
INFERNO-type model is also presented
A variational atomic model of plasma accounting for ion radial correlations and electronic structure of ions (VAMPIRES)
We propose a model of ion-electron plasma (or nucleus-electron plasma) that
accounts for the electronic structure around nuclei (i.e. ion structure) as
well as for ion-ion correlations. The model equations are obtained through the
minimization of an approximate free-energy functional, and it is shown that the
model fulfills the virial theorem. The main hypotheses of this model are 1)
nuclei are treated as classical indistinguishable particles 2) electronic
density is seen as a superposition of a uniform background and
spherically-symmetric distributions around each nucleus (system of ions in a
plasma) 3) free energy is approached using a cluster expansion (non-overlapping
ions) 4) resulting ion fluid is modeled through an approximate integral
equation. In the present paper, the model is described only in its average-atom
version
Application of Hartree-Fock theory of fluctuations to opacity calculation
The Hartree-Fock theory of fluctuations leading to simple formulae for configuration probabilities is used in a Detailed Configuration Accounting calculation of opacity in the case of an iron plasma. A direct Detailed Term Accounting method is also applied. The correlations of subshell occupation numbers, which are accounted for in the HF theory, show small effect on the theoretical spectrum corresponding to conditions of a recent measuremen
A consistent approach for mixed detailed and statistical calculation of opacities in hot plasmas
Absorption and emission spectra of plasmas with multicharged-ions contain
transition arrays with a huge number of coalescent electric-dipole (E1) lines,
which are well suited for treatment by the unresolved transition array and
derivative methods. But, some transition arrays show detailed features whose
description requires diagonalization of the Hamiltonian matrix. We developed a
hybrid opacity code, called SCORCG, which combines statistical approaches with
fine-structure calculations consistently. Data required for the computation of
detailed transition arrays (atomic configurations and atomic radial integrals)
are calculated by the super-configuration code SCO (Super-Configuration
Opacity), which provides an accurate description of the plasma screening
effects on the wave-functions. Level energies as well as position and strength
of spectral lines are computed by an adapted RCG routine of R. D. Cowan. The
resulting code provides opacities for hot plasmas and can handle mid-Z
elements. The code is also a powerful tool for the interpretation of recent
laser and Z-pinch experimental spectra, as well as for validation of
statistical methods.Comment: submitted to "High Energy Density Physics
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