Electrostatic attraction of charged drops of water inside dropwise cluster

Based on the analytical solution of the Poisson-Boltzmann equation, we demonstrate that inside the electrically neutral system of charges an electrostatic attraction can occur between the like-charged particles, where charge Z >> 1 (in terms of elementary charge) and radius R > 0, whereas according to the literature, only repulsion is possible inside non-electrically neutral systems. We calculate the free energy of the charged particles of water inside a cluster and demonstrate that its minimum is when the interdroplet distance equals several Debye radii defined based on the light plasma component. The deepest minimum depth is in a cluster with close spatial packing of drops by type, in a face-centered cubic lattice, if almost all the electric charge of one sign is concentrated on the drops and that of the other sign is concentrated on the light compensation carriers of charge, where the charge moved by equilibrium carriers is rather small. (C) 2013 AIP Publishing LLC.