The coagulation rate of charged aerosols in ionized gases

We obtain analytical expressions for the coagulation rate of aerosols in ionized gases taking into account the statistical distribution of the aerosol charge due to the random nature the charging process. Depending on the asymmetry of the ionic environment, the charge distribution may be bipolar (symmetric charging) or unipolar (highly asymmetric charging). In symmetric charging the attraction between opposite charges is almost exactly counterbalanced by repulsion between like charges and the net effect is a slight increase in the overall coagulation rate. In asymmetric charging all particles carry charges of the same polarity, interparticle interactions are repulsive, and the rate of coagulation decreases. However, the effect of the charge distribution in these systems is to increase the rate of coagulation above the rate that would be obtained if all particles carried the mean charge. This increase is substantial for larger particles in highly asymmetric ionic environments. (C) 1997 Academic Press.