The design and optimization of a new microwave plasma source by numerical simulation

The aim of the work is to design a new compact microwave plasma source with a homogeneous circumferential distribution of the electric field intensity. The software for electromagnetic field simulation combined with design-of-experiments techniques was used to design and optimize the source geometry in terms of energy efficiency and field homogeneity. The basic assumption is that plasma can be described by an equivalent dielectric load. Two relatively simple microwave waveguide plasma sources have been simulated to study the effect of impedance-matching devices on the energy efficiency of the whole system. A microwave waveguide plasma source based on the WR340 waveguide geometry has been assembled to validate the model experimentally. A completely new compact plasma source, which is a toroidal waveguide and an innovative ‘self-adapting’ coupling slot, has been numerically simulated, designed and built. Preliminary tests confirmed the existence of a sufficiently homogeneous five-lobe distribution of the electric field.