The effect of a second grounded electrode on the atmospheric pressure argon plasma jet

Cold atmospheric pressure plasma jet has attracted a great interest of researchers engaged in different areas due to its wide range of applications. In this article, the effect of adding a second grounded electrode (SGE) to the two electrodes plasma jet system was investigated. The jets system consisted of a quartz tube surrounded by two copper strips, which were separated by 40 mm. The SGE was placed below the jet nozzle by 2 mm and 5 mm from its axial. The jet characteristics with and without the SGE were investigated using plasma images, voltage-current waveforms, and emission spectra. Two current pulses per each half a cycle were measured when the SGE was used while one pulse was measured without using it. The second current pulse was much longer than the first one. Argon emission spectra were the most intense lines among all other plasma species even for the measurement out of the flow stream. The OH• emission spectra were higher in the discharge zone than those outside the discharge zone. The presence of the SGE enhanced the emission spectra for all the investigated positions above and in front of the SGE. The transition from laminar to turbulent mode was observed at lower flow rate value without using the SGE and a significant decrease in jet length was detected at 3.5 slpm with and without using the SGE. This system is scalable by using multi-SGE to form a large volume plasma, which is strongly required for biomedical and industrial applications. © 2020 IOP Publishing Ltd