Electrodynamics of microwaves in a coaxial non-regular waveguide partly filled with plasma

Abstract

The electrodynamics of microwave fields (f = 2.45 GHz), propagating inside a coaxial non-regular system with a plasma-ball at the tip of a central electrode, have been simulated. For this purpose, the time-dependent Maxwell's equations have been solved numerically in a two-dimensional grid. To outline the main properties of distribution of the microwave energy in such a system, various shapes and densities of quasi-neutral uniform plasma have been investigated. The simulations have been carried out for hydrogen in the range of pressures 0.5–8 Torr and densities 0.2–20nc. It was found that for under-dense plasma of any given configuration the absorbed power mostly concentrated near the tip of the internal electrode. For over-dense plasma, the microwave power is located both near the electrode and inside the surface layer of the plasma-ball. This distribution of absorbed microwave power is similar to the plasma light emission distribution observed in experiments. Transformation of the TEM wave into the surface wave has been demonstrated.