Distribution of electrons, ions, and fine (dust) particles in cylindrical fine particle (dusty) plasmas: drift-diffusion analysis

Based on the drift-diffusion equations, the behaviour of electrons, ions and fine particles in fine particle plasmas is analysed both analytically and numerically. The cylindrical symmetry of the system is assumed and the cases of up to two species (sizes) of fine particles are considered. It is shown that, in the domain where fine particles exist, the charge neutrality is satisfied to a much higher accuracy, so that the electrostatic potential and the electron distribution are almost flat, and the change in the negative charges due to fine particles is compensated by the ion distribution. This occurs when the charge density of particles multiplied by their charge number exceeds the electron and ion charge densities, and is analytically attributed to the participation of fine particles to the screening of the space charge. The condition for the formation of void at the centre is obtained and the behaviour of particle distribution for parameters around the condition is observed. In the case of two species, the possibility is shown that smaller particles are distributed inside of the domain of larger particles and, when the larger ones form a void, it is filled with smaller ones, the enhanced charge neutrality being recovered. (paper)