Analytical model of particle charging in plasmas over a wide range of collisionality

An accurate prediction of the particle charge in plasmas is of fundamental importance for a wide range of problems from the study of dusty or complex plasmas to the controlled synthesis of nanoparticle materials in plasmas. Despite its known deficiencies, the orbital motion limited (OML) theory, which strictly applies only to collisionless plasmas, is the most widely used model to describe particle charging. This paper develops a simple, analytical model to describe the charging of particles in plasmas over a wide range of pressures and particle sizes. In spite of its simplicity, excellent agreement is found with results of a self-consistent molecular dynamics Monte Carlo model and with experimental results found in the literature. In particular, the model presented here provides significant improvements compared to the OML theory.