Charges of a single grain and the grain in a cloud: Theory and experiments

The effect of cloud density on the grain charging is of great importance in complex plasma physics. The quasi-neutrality condition brings about changing of ratio of a spatially averaged ion density to electron density in the dust cloud. Strong interaction between ions and highly charged grain complicates the analysis of the effect of ion density increasing on ion flux on the grain. The theoretical approach to ion flux correction on the grain space charge by the use of effective ion density instead of spatially averaged density is discussed. The experimental measurements of charges of solitary grains and the grains in the cloud under similar plasma parameters are used to prove the proposed approach.