Electric field-driven Rayleigh–Taylor-like instability in binary complex plasma

This study uses two-dimensional molecular dynamics simulations to explore Rayleigh–Taylor-like instability in strongly and weakly coupled binary complex plasmas when heavier dust particles are positioned above the lighter ones, having the same charge-to-mass ratio, in a planar configuration. Langevin dynamics simulations are used to study the evolution of perturbations at the interface between these two distinct species of charged dust particles, subject to an externally applied electric field and an equilibrium charge density gradient. We have performed analytical calculations to determine the growth rate of instability under both strongly and weakly coupled dusty plasma regimes. A striking feature of strongly coupled plasma is that there exists a critical value of wavenumber kc where the growth rate vanishes and above which the growth rate attains negative values, or damping takes place; meaning the perturbations having wavenumber k>kc do not evolve into instability. This critical wave number kc shows a dependence on the electric field, relaxation time, viscosity coefficient, screening parameter, mass density, and charge density of dust particles. Theoretical predictions are subsequently validated through molecular dynamics simulations, enabling the reproduction of the instability in binary complex plasma. In these cases, instability ultimately causes mixing among the charged species. The study comprehensively analyzes the growth rate as a function of various system parameters, and it offers deeper insight into the underlying physical mechanisms.