Can charge fluctuations explain particle growth in low-pressure plasmas?

Particles in low-pressure plasmas carry a substantial negative charge and are subject to strong repulsion. However, the instantaneous particle charge undergoes fluctuations whose magnitude and duration can be substantial. Excursions of the charge from the mean value alters the particle behavior and results in interactions that are substantially different from the average. We calculate the rate of particle agglomeration taking into account the statistical distribution of the particle charge. We find that effect of fluctuations is to always increase the rate of agglomeration, especially for small particles. The collision cross section of larger particles is enhanced significantly, but the overall collision rate remains too low. Under these conditions, growth is fueled by small particles and is predicted to result in narrow size distributions.