Evaluating ion dynamics through Coulomb and Yukawa interaction potentials in one-component strongly coupled plasmas.

Abstract

Atmospheric pressure helium plasmas are investigated through molecular dynamics simulations at room temperature (300 K) for various ionization fractions (χ_{i}=10^{-1}-10^{-5}) in the strongly coupled regime (ion coupling parameter, Γ_{i}∼1-10) employing Coulomb and Yukawa interaction potentials. The role of electron screening in ion dynamics and energetics is examined through ion and gas temperatures, mean squared displacement of ions, ion coupling parameter, and radial distribution function of the system. It is found that electron screening in the Yukawa potential significantly limits the disorder-induced heating (DIH) mechanism for strongly ionized plasmas (χ_{i}≥10^{-3}). Whereas, ions show a prominent subdiffusive behavior associated with the DIH during the nonequilibrium phase for the Coulomb potential. The DIH mechanism is explained using a model based upon the conservation of energy. However, for weakly ionized plasmas (χ_{i}≤10^{-4}), the maximum ion temperatures are almost similar for both potentials. Furthermore, electron screening affects the separation distance and arrangement of the ion-neutral pairs for all the values of χ_{i}. In general, Yukawa potential results in a lower mean potential energy of the interacting particles, which is energetically favorable for the stability of the system.