Interaction force between two finite-size charged particles in weakly ionized plasma

Abstract

The results of numerical studies of the interaction forces between two finite-size charged spherical conductive particles embedded into weakly ionized strongly collisional isothermal plasma-like medium are presented. The studies are performed for the case of particles with fixed electric charge under the assumption that particles do not absorb electrons and ions from the surrounding plasma (colloidal particles) as well as for particles charged by plasma currents (grains). In the first case the Poisson-Boltzmann model was used and in the second the dynamics of grain charging is described in the drift-diffusion approximation. It is shown that at the large distances the interaction force between colloidal particles has the Debye screened asymptotic while for the grains the Coulomb-like behavior is observed. The dependence of the grain charge collected due to the plasma particle absorption on the distance between two grains is studied. The possibility of introducing effective Coulomb description of finite-size grain interaction in weakly ionized strongly collisional plasma is discussed.