Charging and coagulation of dust in protoplanetary plasma environments

TL;DR

This study models dust coagulation and charging in protoplanetary plasmas, revealing how plasma type and charge influence aggregate growth, structure, and size, with implications for understanding disk environments.

Contribution

It introduces a combined model of particle coagulation and charging in plasma environments, analyzing how plasma conditions affect dust aggregate properties in protoplanetary disks.

Findings

Charged aggregates grow larger and more massive than neutral ones.

Lorentzian plasma produces fluffier, larger aggregates than Maxwellian plasma.

Aggregate structure measurements can infer disk parameters during formation.

Abstract

Combining a particle-particle, particle-cluster and cluster-cluster agglomeration model with an aggregate charging model, the coagulation and charging of dust particles in various plasma environments relevant for proto-planetary disks have been investigated. The results show that charged aggregates tend to grow by adding small particles and clusters to larger particles and clusters, leading to greater sizes and masses as compared to neutral aggregates, for the same number of monomers in the aggregate. In addition, aggregates coagulating in a Lorentzian plasma (containing a larger fraction of high-energy plasma particles) are more massive and larger than aggregates coagulating in a Maxwellian plasma, for the same plasma densities and characteristic temperature. Comparisons of the grain structure, utilizing the compactness factor, {\phi}{\sigma}, demonstrate that a Lorentzian plasma environment results in fluffier aggregates, with small {\phi}{\sigma}, which exhibit a narrow compactness factor distribution. Neutral aggregates are more compact, with larger {\phi}{\sigma}, and exhibit a larger variation in fluffiness. Measurement of the compactness factor of large populations of aggregates is shown to provide information on the disk parameters that were present during aggregation.