Influence of the plasma environment on atomic structure using an ion-sphere model

Plasma environment effects on atomic structure are analyzed using various atomic structure codes. To monitor the effect of high free-electron density or low temperatures, Fermi-Dirac and Maxwell-Boltzmann statistics are compared. After a discussion of the implementation of the Fermi-Dirac approach within the ion-sphere model, several applications are considered. In order to check the consistency of the modifications brought here to extant codes, calculations have been performed using the Los Alamos Cowan Atomic Structure (cats) code in its Hartree-Fock or Hartree-Fock-Slater form and the parametric potential Flexible Atomic Code (fac). The ground-state energy shifts due to the plasma effects for the six most ionized aluminum ions have been calculated using the fac and cats codes and fairly agree. For the intercombination resonance line in ${\mathrm{Fe}}^{22+}$, the plasma effect within the uniform electron gas model results in a positive shift that agrees with the multiconfiguration Dirac-Fock value of B. Saha and S. Fritzsche [J. Phys. B 40, 259 (2007)]. Last, the present model is compared to experimental data in titanium measured on the terawatt Astra facility and provides values for electron temperature and density in agreement with the maria code.

Figure 1

Influence of different free-electron distributions on the self-consistent plasma potential for H-like neon at $T_e=1\text{eV}$ and $N_e={10}^{24}{\text{cm}}^{-3}$. The electron distance to the nucleus $r$ is expressed in units of the ion-sphere radius $R_0=2.438a_0$. The potential is obtained from cats using the HFS path.

Figure 2

Radial wave functions for $1s^{2}2s^2$ and $1s^{2}2s2p{}^3{P}_1$ levels of ${\mathrm{Fe}}^{22+}$ at a density of $N_e=5\times {10}^{24}{\text{cm}}^{-3}$ calculated with the UEGM. The electron distance to the nucleus $r$ is expressed in units of the ion-sphere sphere radius $R_0=1.921a_0$. The wave functions have been computed from cats (HFR).

Figure 3

Difference between the plasma potential obtained with the linear interpolation method and the case with $R_0$ on the grid. The density used is $N_e=5.1829\times {10}^{23}{\text{cm}}^{-3}$, and the temperature $k{T}_e=100\text{eV}$. The electron distance to the nucleus $r$ is expressed in units of the ion-sphere radius $R_0=3.2457a_0$.