Electrical and optical diagnostics of plasma jet generated by needle-plate dielectric barrier discharge at atmospheric argon

An atmospheric argon plasma jet was obtained with a needle-plate dielectric barrier discharge system. The discharge gap was kept at 4 mm and the argon gas flow rate was 0.5 L/min. A test capacitor and a test resistance were connected in series in the circuit, and the discharge current and the transport charge were measured simultaneously. The average discharge power in a period of the applied voltage was calculated by Lissajous figure. The plasma jet was investigated spatially by optical emission spectroscopy, and the electron density was estimated by Stark broadening of ArI 696.54 nm. It is found that the discharge is asymmetric at different discharge phases, and more discharge current pulses are generated during the positive half cycle of the applied voltage. In addition, with the increasing of the applied voltage, the pulse number and the discharge power increase. Moreover, the plasma density is in an order of 1015 cm-3. With the increasing of the distance from the needle tip, the electron density of the plasma jet decreases from 2.94×1015 cm-3 to 2.28×1015 cm-3. The results show that the electric field plays an important role in the discharge current number and the spatial distribution of the electron density. ©, 2014, Chines Academy of Sciences. All right reserved.