A comparative study of continuum and kinetic simulations of GHz - THz microwave microplasmas

Microplasmas ignited using high-frequency excitation are becoming an active area of research due to the myriad applications and the ability to be sustained at low powers ($\approx$ mW) and longer lifetimes. A majority of the computational studies reported thus far for microwave microplasmas have utilized a fluid approach using a drift-diffusion approximation with the concept of an effective electric field often recommended for better accuracy. Our group has previously reported kinetic (using PIC-MCC simulations) and fluid simulations (using full-momentum equations) for argon microwave microplasmas ignited at excitation frequencies up to 4 GHz and a specified current density with good agreement between the two methods at the chosen operating conditions. The main goal of this talk is to report our recent work on extending this comparative study to frequencies up to 320 GHz. Specifically, one-dimensional kinetic and continuum simulations at 1 mW, 10 mW, 50 mW and 100 mW are presented to compare and contrast the frequency response and electron dynamics predicted by the two simulations techniques. Phase plots of electron heating will be presented demonstrating the importance of stochastic heating even in atmospheric pressure plasmas at excitation frequencies as high as 20 GHz.