A block-structured nonuniform meshing technique for reducing the degrees-of-freedom in hybrid particle-in-cell plasma simulations

In this work we discuss a block-structured nonuniform meshing technique for multi-scale plasma simulations of plasma sheaths and scrape-off layers, suitable to implementation in hybrid Particle-in-Cell (PIC) schemes that consider kinetic ions and Boltzmann electrons. The meshing scheme is designed to support large-scale fusion plasma domains (spanning tens of meters) with a substantially reduced number of degrees-of-freedom (DOF) compared to simulations employing a uniform mesh. We show that the solution derived at low DOFs maintains the same level of accuracy as solutions obtained from highly refined uniform meshes, still maintaining particle noise under control. The meshing scheme can be equally applied to both 1D and 2D plasma domains. This reduction in DOFs leads to a significant reduction in computational cost while keeping total count of computational particles the same for corresponding cases, making it a valuable tool for cost-effective, multi-scale fusion plasma simulations.