Measurement and interpretation of swarm parameters and their application in plasma modelling

TLDR

This review surveys the past decade of charged‑particle swarm physics, emphasizing the need to revive experiments and their relevance for advancing plasma modeling. The authors examine swarm coefficient measurements, data availability, guidance on ion and fast‑neutral information, and the interpretation of transport data and kinetic phenomena to inform accurate plasma model construction. They identify key kinetic‑theory insights and data subsets essential for refining plasma models, illustrate their application in Townsend discharges, afterglows, breakdown, and atmospheric phenomena, and argue that swarm physics must be used to validate or improve model fidelity.

Abstract

In this review paper, we discuss the current status of the physics of charged particle swarms, mainly electrons, having plasma modelling in mind. The measurements of the swarm coefficients and the availability of the data are briefly discussed. We try to give a summary of the past ten years and cite the main reviews and databases, which store the majority of the earlier work. The need for reinitiating the swarm experiments and where and how those would be useful is pointed out. We also add some guidance on how to find information on ions and fast neutrals. Most space is devoted to interpretation of transport data, analysis of kinetic phenomena, and accuracy of calculation and proper use of transport data in plasma models. We have tried to show which aspects of kinetic theory developed for swarm physics and which segments of data would be important for further improvement of plasma models. Finally, several examples are given where actual models are mostly based on the physics of swarms and those include Townsend discharges, afterglows, breakdown and some atmospheric phenomena. Finally we stress that, while complex, some of the results from the kinetic theory of swarms and the related phenomenology must be used either to test the plasma models or even to bring in new physics or higher accuracy and reliability to the models.