Numerical Design of the Cavity for the Uniform Atmospheric Microwave Plasma Source

Abstract

A single ridge cavity was designed for the 60 kw, 915 MHz uniform atmospheric microwave plasma source which does not need an igniter for the initial discharge. The single ridge cavity in the shape of a resonator was built in the grid structures for the wide cavity torch of the atmospheric pressure microwave plasma. This cavity was studied by using an analytical calculation with a lumped circuit approximation and by using a simulation with the commercial 3D HFSS code. The designed plasma cross-sectional area was uniformly 810 mm 5 mm. We developed a design formula that used the lumped circuit approximation and we compared its results with the results of the HFSS simulation. The analytically calculated cavity frequency, 915 MHz, matched the HFSS's simulation result, 904 MHz, well for the fundamental TE10-like mode. A self-dischargeable study was conducted for the breakdown feasibility in the cavity gap region These cavities showed a uniform electromagnetic wave distribution between the grids through which a large-sized microwave plasma could be generated when the cavities were connected in parallel pairs so that the crests of the electric eld intensity compensate for its troughs.