TIME-DEPENDENT FRICTION ON A CHARGED TRACER IN A BROWNIAN MULTICOMPONENT PLASMA

From the generalized Langevin equation theory of tracer diffusion, we derive approximate analytic expressions for the dynamic friction funct ion of a finite-sized charged tracer undergoing Brownian motion in a m ulticomponent ionic solution of point-like ions. We find that results such as Schurr's expression for the static friction of a colloidal mac roion, Onsager's limiting law of the relaxation effect in ionic soluti ons, and Hess and Klein's result for dynamic self-friction in the Brow nian one-component plasma, follow as particular cases, or limits, with in well-defined approximations.