Coagulation of dielectric dust grains due to variable asymmetric charging

Observational evidence of electrical forces acting significantly on small solids is present for both the modern solar system in Saturn’s rings (1) and the ancient solar system in chondritic meteorites (2). It is likely that grain-grain coagulation rates are affected by the distribution of charges on small grains. Plasma particle impacts and photoelectric effects can provide the charges. It appears that some charging is inevitable and that plasma grain interactions need to be evaluated to determine the size of the effect on coagulation rates. We apply the results of our previous charging work (3, 4, 5) to models of the protoplanetary nebula. It is expected that the protoplanetary nebula is weakly ionized (6) except in certain instances and locations such as: solar flares in the interior, ultraviolet radiation at the outer boundary, and during enhanced luminosity of the star. Since the grains we study are non-conducting and show strong dipole moments in flowing plasma, we modify the geometric cross sections...