Self-consistent modeling of atmospheric micro-plasmas produced by a microwave source

This paper presents the self-consistent modeling of argon micro-plasmas, produced by a microwave source (2.45 GHz) at atmospheric pressure [1]. Simulations use a 1D, stationary hybrid code that solves the fluid-type transport equations for electrons, positive ions Ar$^{+}$ and Ar$_{2}^{+}$, and the electron mean energy; the rate balance equations for the main neutral species; Poisson's equation for the space-charge electrostatic field; Maxwell's equations for the electromagnetic excitation field; the gas energy balance equation for its temperature distribution; and the kinetic electron Boltzmann equation considering several direct and stepwise electron collisions processes. The model uses a kinetic scheme that considers the atomic excited states Ar(4s) and Ar(4p), two excimer states Ar$_{2}$* and Ar$_{2}$**, and two ionization states associated to the atomic and the molecular ions. The model predicts power densities of 1-5 kW cm$^{-3}$ and gas temperatures of 400-700 K, for electron densities of $\sim $10$^{13}$-10$^{14}$ cm$^{-3}$, in agreement with measurements. Simulations exhibit a strong dependence on the gap-size and the electron density. [1] J. Greg\'{o}rio et al, these proceedings.