Influence of different kinetic heating mechanisms on the dynamics of a trapped Brownian particle in a complex plasma

Abstract

Combined effect of random forces of different origins and electrostatic confinement on the dynamics of a charged Brownian particle in a plasma is investigated. Analytical equations for the effective kinetic temperature, mean square displacement (MSD), mass transfer, and velocity autocorrelation functions (VAF) of a free and trapped microparticle under the action of two random forces governed by Gaussian and Ornstein–Uhlenbeck processes are derived. The results obtained are considered on examples of solitary passive microparticles with fluctuating charges due to the discrete charging process or inhomogeneity of the surrounding plasma, active light-absorbing particles with rotational fluctuations, and strongly coupled systems with nonreciprocal interparticle interactions. The applicability of the Langevin equations with a thermal noise temperature above the ambient gas temperature to model the dynamics of dust particles in a complex plasma is discussed. It is shown that, under certain conditions, the well-known Uhlenbeck–Ornstein–Wang equations for the MSD and VAF fail to describe the oscillations of both a solitary particle and a particle in a strongly coupled monolayer system suspended in a gas discharge.