Charging and Coagulation of Dust in Protoplanetary Plasma Environments

Combining a particle–particle, particle–cluster, and cluster–cluster agglomeration model with an aggregate charging model, the coagulation and charging of dust particles in plasma environments relevant for protoplanetary disks have been investigated, including the effect of electron depletion in high dust density environments. The results show that charged aggregates tend to grow by adding small particles and clusters to larger particles and clusters, and that cluster–cluster aggregation is significantly more effective than particle–cluster aggregation. Comparisons of the grain structure show that with increasing aggregate charge the compactness factor, ϕ σ , decreases and has a narrower distribution, indicating a fluffier structure. Neutral aggregates are more compact, with larger ϕ σ , and exhibit a larger variation in fluffiness. Overall, increased aggregate charge leads to larger, fluffier, and more massive aggregates.