Structured Multi-Resolution PIC Code for Electromagnetic Plasma Simulations

The objective of this proposal is to demonstrate the feasibility of structured adaptive mesh refinement (SAMR) for increasing the global accuracy (i.e., spatial and temporal resolution) of electromagnetic particle-in-cell (EM-PIC) models of electronic devices and plasma configurations. The SAMR technique covers a complex geometry domain with a “parent” mesh of computational nodes superimposed with block-structured finer (“child”) patches, which resolve small scale features. Each patch preserves regular gridding and, therefore, enables easy particle tracking and accurate computation in its interior due to the symmetry of finite-difference (FD) or finite-volume operators. To capture the exact model geometry and avoid numerical errors associated with standard stair-stepped boundary approximations, SAMR can be combined with cell cutting. This leads to second-order convergence characteristic of high-fidelity conformal FDTD models. This proposal offers two different strategies, including a novel “mixed resolution” technique, for mitigating numerical errors arising in SAMR EM-PIC simulations due to abrupt changes in the particle weighting scheme and the finite-difference approximation at coarse-fine mesh interfaces. The proposed numerical schemes promise to effectively mitigate wave reflection, spurious force and charge/current mismatch effects introduced by SAMR at fine patch boundaries.