Effective-Medium Modeling of a Meanderline Metamaterial-Enhanced Resistive Wall Amplifier Circuit for Particle-in-Cell Simulations

Theory and simulations predict the metamaterial-enhanced resistive wall amplifier (MERWA) may offer improvements to megawatt-level high-power microwave (HPM) amplifiers in terms of combined bandwidth and gain rates. A low-power proof-of-concept test prototype has been designed using a metamaterial (MTM) consisting of a linear array of periodically spaced thin lossy meandered wires. Direct simulations of these arrays of thin meandering wires using typical 3-D particle-in-cell (PIC) solvers are inaccurate, creating significant challenges for obtaining trustworthy hot test simulations of the prototype device. This work enables predictive PIC simulations of the experimental MERWA prototype by replacing the thin lossy wire structure with an equivalent effective-medium model. We find that a finite-width rod having an anisotropic Drude-Lorentz permittivity is a suitable model to replace the lossy wire MTM structure. We detail our modeling process and assumptions, fitting procedures, and model fitting results. The model is validated by comparing PIC simulations to experimental results.