Diagnosis of an Atmospheric Pressure Plasma Jet Using a Single Dielectric Barrier Discharge

An optical investigation is presented for a plasma jet device with utilizes a discharge mechanism between a bare metal electrode and a dielectric barrier on a ground electrode. The length of the plasma plume increases linearly with increasing driving voltage, but it has maximum values for variations in the gas flow rate. If the gas flow rate is too small or too large, the plume length is shortened. The plasma plume is observed to be successive motion of plasma bullets that are generated only when the voltage on the bare electrode is positive. The speed of the plasma bullets varies from a few to tens of km/s at different observation positions, and it varies with changing gas flow rate and the driving voltage. A larger gas flow rate results in a longer discharge formation and a longer duration time of the plasma jet.