Efficient Dynamic Mesh Refinement Technique for Simulation of HPM Breakdown induced Plasma Pattern Formation

Abstract: Numerical simulation of the complex plasma dynamics associated with high power, high frequency microwave breakdown at high pressures, leading to the formation of filamentary plasma structures such as self-organized plasma arrays, is a computationally challenging problem. The widely used 2D EM-plasma fluid model, which accurately captures the experimental observations, requires a run-time of several days to months to simulate standard problems due to stringent numerical requirements in terms of cell size and time step. In this paper, we present a self-aware mesh refinement algorithm which uses a coarse mesh and a fine mesh that dynamically expands based on the plasma profile topology to resolve the sharp gradients in E-fields and plasma density in the breakdown region. The dynamic mesh refinement (DMR) technique is explained in details and its performance has been evaluated using a standard benchmark microwave breakdown problem. We observe a speedup of 8 (of the order of $O(r^{3})$, when refinement factor ($r$) is 2) compared to a traditional single uniform fine mesh based simulation. The technique is scalable and performs better when problem size increases. We also present a comprehensive spatio-temporal visual analysis to explain the complex physics of HPM breakdown, leading to self-organized plasma filamentation.