Plasma ignition in a quarter-wavelength microwave slot resonator
J. Phys. D: Appl. Phys., vol. 41, no. 19, p. 194003 (2008).
© Institute of Physics and IOP Publishing Limited 2008. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the Institute of Physics and IOP Publishing Limited.
A new microwave plasma source concept, particularly for use in the atmospheric pressure region, is presented where impedance matching is realized by a quarter-wavelength waveguide resonator structure. The waveguide is formed by a slot of 100µm width machined into a copper sheet of 50mm × 10mm with a thickness of 200µm. The slot length for a resonance frequency of 2 GHz is approximately 37.5 mm. This allows generating voltages high enough for ignition of an atmospheric plasma by this very small, simple and easy-to-fabricate structure. After ignition, the plasma extends over approximately 12mm length of the slot, so a high electrode lifetime can be expected. Furthermore, the planar geometry of this source facilitates up-scaling to array configurations, which allows realization of a distributed source for treating large areas. Basic ignition parameters are investigated. Statistics for multiple ignitions are presented and the resulting Paschen characteristics are shown in the pressure region from 100 Pa to atmospheric pressure.
Ferdinand-Braun-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, D-12489 Berlin, Germany