On the Cut-off Distance and the Classical Energy-averaged Electron-ion Momentum Transport Cross Section in Ideal and Nonideal Plasmas

TL;DR

This paper introduces a physically justified cut-off distance for plasma charge screening, deriving a new momentum transport cross section expression that improves agreement with experimental data over previous models.

Contribution

It proposes a new physically consistent cut-off distance and derives a closed-form expression for the momentum transport cross section in plasmas.

Findings

Better agreement with experimental conductivity data.

Improved physical behavior over previous models.

A simple Coulomb logarithm approximation.

Abstract

The wide use of a speed-independent distance as a cut-off impact parameter together with Rutherford's scattering formula, within the cut-off theory, to account for charge screening in plasma environment embodies a clear inconsistency. A new physically justified choice of the cut-off distance is introduced and used to derive a closed form expression for the effective momentum transport cross section. A simple approximation for the present Coulomb logarithm, free of special functions, is also presented and assessed. A comparison with experimentally recovered data for the reduced Coulomb conductivity showed better agreement and better physical behavior of the present expressions compared to previous cut-off expressions in the literature.