Effect of the Grounded Electrode on Cold Ar Atmospheric Pressure Plasma Jet Generated With a Simple DBD Configuration

Nonthermal and low-temperature plasmas has been a subject attracting great interest of scientists engaged in different fields of science and application. In this paper, a cold Ar plasma jet is generated under atmospheric pressure by using a dielectric barrier discharge configuration device equipped with a copper ring electrode and an aluminous plate grounded electrode driven by a sinusoidal excitation voltage at 10 kHz. The distance (d, for short) between the grounded electrode and the nozzle of the quartz tube is set at 10, 20, and 30 mm, respectively. The jet characteristics are investigated by electrical and optical diagnostics, including discharge images, voltage-current waveforms, Lissajous figures, and optical spectrum. The electric discharge and plasma parameters, such as discharge power, transported charges, electronic excitation temperature, etc., with different d are calculated and compared. Furthermore, the influence of the location of the grounded electrode on the characteristics of plasma jet is also studied. The experimental results show that the largest discharge power is generated with d = 10 mm, while the electron density and electronic excitation temperature (EET) of plasma jet will be increasing for d = 20 mm. Thus keeping reasonable distance between the grounded electrode and the nozzle of quartz tube not only can reduce the discharge power, but also improve the electron density and EET of the plasma jet, which contributes to practical application of this jet device.