Bystrenko T. Shielding of highly charged macroparticles and related phenomena in colloidal plasmas

Nonlinear effects in the shielding of a cylindrical macroparticle in an equilibrium plasma are examined within the Poisson-Boltzmann theory. The behavior of the relative effective charge, including the case of small radii of macroparticle, is considered. The range of applicability of the linear theory is established. It is shown that the nonlinear effects are significant for small radii and strong coupling constant. The thickness of the nonlinear layer increases with the coupling constant, but remains limited by the size of the order of the Debye radius. Effects of charging plasma currents on the shielding of a charged dust particle in a discharge plasma are considered on the basis of the linearized version of the orbital motion limited approximation. The behavior of the screened potential is examined. It is shown that, for the parameters typical for laboratory dusty plasmas, the charging processes do not significantly change the behavior of the effective potential predicted by the equilibrium linear screening Deryaguin-Landau-Verwey-Overbeck theory. Significant deviations are observed in the case of macroparticles of larger sizes - of the order of the Debye length. Effects of trapped ion states on the shielding of a charged dust particle in a discharge plasma are considered on the basis of the nonlinear orbital motion limited approximation. It is established that the bound ionic states in collisionless plasmas exist only in a limited region near the dust grain, which is the result of the asymptotical behavior of the effective potentials inversely proportional to the squared distance.