Mean excitation energies for ions in gases and plasmas

Abstract

A variational approach yields accurate upper and lower bounds for mean excitation energies and other related parameters describing the stopping of nonrelativistic point charges by isolated species and ions embedded in dense and hot matter of relevance to particle-driven inertial fusion. The resulting I compares nicely with previous ones by Hartree–Fock–Slater and with experimental data when available. An efficient pseudo-analytic formula based on the Thomas–Fermi method is obtained, together with a cubic spline interpolation variationally improved. It is shown that in high temperature plasmas (kBT≥10 eV) mean excitation energies are significantly smaller than their cold homologue.