“…To prevent the unwanted transition of glow to arc discharge, a dielectric barrier that can easily control the current during discharge is commonly used, thus resulting in AC discharge [ 19 , 20 , 21 , 22 , 23 ]. When generating a DC discharge, it is common to expose the powered electrode to the discharge space, include a proper ballast resistor in the circuit to control the current, and ground the counter electrode [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. However, even when the tip of the tungsten wire electrode of the newly designed AP-plasma reactor was exposed to the discharge space, a ballast resistor was not needed because the AC voltage was applied at a frequency of about 30 kHz, and the glow discharge occurred in a single electrode structure without a ground electrode.…”