Explicit Particle Mover With Damping for Electrostatic Particle-In-Cell Simulations

Short-wavelength numerical fluctuations limit the choice of space step in conventional explicit particle-in-cell (PIC) simulations, and it is meaningful to study explicit particle movers with damping of numerical noises. In this work, we propose a strategy to guide the construction of such movers, in which the electric field acceleration is smoothed in the time domain and the unknown future acceleration is split into the sum of a known major quantity and an unknown minor quantity, with the latter being estimated as a combination of a series of known quantities through line approximation. We further design an explicit particle mover with damping for electrostatic PIC simulations. Dispersion analysis of cold plasma Langmuir wave shows that the mover provides damping of modes depending on the product of mode frequency and time-step, wherein the damping is strong at large time-step or high-frequency, which is helpful to reduce short-wavelength noise modes. The results of numerical experiments indicate numerical heating caused by poor resolution of electron Debye length can be suppressed effectively by the explicit PIC simulations running with the new mover while the accurate descriptions of desired physical phenomena are retained. Meanwhile, the mover tends to cool particles, with the cooling rate being considered tolerable in the case the product of the motion frequency and time-step is small. We believe that the proposed mover here is helpful for people to research the bounded plasma driven by RF source.