Reply to "Longitudinal Diffusion Coefficients Misnamed," by R. N. Varney

Abstract
Varney has recently applied random-walk methods to discuss the longitudinal diffusion of gaseous ions drifting in an electric field, and he obtained results which differ from those obtained by solution of the diffusion equation. Varney's analysis leads him to state that the measured longitudinal diffusion coefficients are not diffusion coefficients at all. Several arguments are presented here to refute Varney's findings.