Effect of ion correlations on high-frequency plasma conductivity

Abstract

In an earlier work the ac conductivity of a plasma was investigated by means of an elementary model. The validity of this model has been borne out by a rigorous treatment of plasma at thermal equilibrium. The elementary model is now extended to include the effects of ion correlations for arbitrary fixed ion distributions. For thermal equilibrium correlations it is found that the ion shielding reduces the maximum effective impact parameter by the factor (1 + Z)1/2 (i.e., both ions and electrons contribute to the shielding) for frequencies low compared to the plasma frequency ωp. For frequencies high compared to ωp, the previous results obtain. The resistance due to the excitation of longitudinal waves at frequencies just in excess of ωp is reduced by the factor (1 + Z)-1. However, if large-amplitude (nonthermal) ion fluctuations are present, the longitudinal wave contribution to the resistance may be greatly enhanced.