Hybrid plasma generation triggered by a shunting arc discharge using a positively biased electrode

The recent trend in thin film deposition is to prepare ceramic films capable of enduring violent environments, such as corrosive pollutant gases with high temperatures. Different kinds of plasma species existing in the same space are advantageous in order to facilitate a reactive deposition between the gaseous and metallic species. In this paper, we study a carbon shunting arc that triggers a gas discharge using a positively biased electrode. An electrode with a positive voltage of up to 500 V was set nearby the carbon shunting arc source. Nitrogen, methane, or argon was used as an ambient gas. The induced plasma was generated with a time delay from the moment of the generation of the shunting arc. The electrical and optical characteristics of the discharge were studied. The onset time of the induced plasma as a function of the ambient gas pressure has a Paschen-like V-shaped characteristic. The generated plasma includes both carbon and gaseous species. At the surface of the positively biased electrode, both spectrum emissions of carbon and gaseous species are observed, by which the plasma is confirmed to be mixed. This is based on the spectrum observation in addition to the change in the color of the plasma. A shunting arc is an easy method used in generating a hybrid plasma consisting of metallic (including carbon) and gaseous species. This method promises to efficiently prepare ceramic films by reactive deposition. This method is simple, and both plasma species, i.e., those of metal and gas particles, are easily mixed. The carbon shunting arc plasma plays both the roles of supplying the carbon species and triggering a gaseous plasma as an induced plasma. Index Terms--Arc discharge, emission spectrum, hybrid plasma, Paschen's law, shunting arc discharge.