Electric field strengths within a micro cavity plasma array measured by Stark shift and splitting of helium

Over the last years micro-structured plasma devices have received increased attention for decomposition and reformation of volatile organic compounds (VOC) [1]. Here, we present a metal-based microcavity reactor which is a convenient alternative to silicon-based devices. This layer-structured reactor consists of a nickel foil operating as an electrode and an electrically grounded magnet. Both electrodes are separated from each other by a 40 µm thick dielectric ceramic foil. The nickel foil consists of four sub-arrays where hundreds to thousands of cavities in the 100 µm range are arranged equally. To obtain more control over charged particles, the electric field is of high importance. Here, the Stark splitting and shifting of the allowed 492.19 nm Helium line and its forbidden 492.06 nm counterpart are exploited to investigate the electric field strengths. By using a combination of a plane grating spectrometer and an attached ICCD camera the typical displacement of about 0.2 nm between both transitions can be resolved. With this technique spatial integrated and phase-resolved electric field strengths with a time resolution up to 1 µs can be measured for this reactor depending on typical operation and geometric parameters. Depending on the polarity of the applied voltage, the electric field strengths increase with smaller cavity diameters up to 60 kV cm^-1.

[1] A. Koutsospyros et al. Int. J. Mass Spectrom. 233 305-315