C-V Characterization On The DBD In Argon For Plasma Jet At Atmospheric Pressure

A lot of experiments and simulations on uniform atmospheric-pressure discharge (APG) have been motivated by numerous potential applications on industry. In recent years, Atmospheric pressure cold plasma jet is a kind of uniform plasma generated technology. In this paper, a plasma jet of argon has been achieved using dielectric barrier discharge (DBD) in flowing argon at atmospheric pressure. A sequence of discharge current pulses of the argon plasma jets has been characterized for each half cycle. The nature of the discharge multi-pulses have been investigated schematically.By recording the discharge voltage and current waveforms, the discharge current pulses under various discharge circumstances have been analyzed in aspects of the transient onset voltage gap between adjoining current pulses, the peak amplitude, the temporal width, the quantity of discharge and the discharge power for the current pulses, according to the external discharge conditions including the gas flow rate, the interelectrode gap, and the area of ground electrode. The results show that the multiple current pulses appeared per half cycle due to the feedback electric field generated by charges accumulated on the dielectric surface. If all the discharge conditions but the gas flow rate are kept invariable, the current peak, the temporal width, discharge quantity and discharge power don't change remarkably. However, when the area of ground electrode is decreased, the current peak, pulse widths discharge quantity and discharge power are decreased. If the interelectrode gap is changed, the pulse width grows with bigger interelectrode gap, while the current peak, discharge quantity and discharge power decrease.The multi-pulses of the discharge current in helium DBD are easily formed in a half circle and therefore many simulations have been done to reveal the forming mechanism of the multi-pulses. It has been recognized that the long-life metastables of helium and their fast diffusion are the key factors for the multi-pulse discharge mode in helium DBD. In order to make clear the physics of the glow-like mode in flowing argon DBD, the multi-pulses of the discharge currents in helium and argon plasma jets have been compared in the aspects of the transient onset voltage gap between the adjoining current pulses, current peaks, pulse widths, discharge quantity and power. With all the investigated circumstances, the multi-pulse feature of the discharge current is shared in both argon and helium plasma jet discharge. However the transient onset voltage gap between the adjoining current pulses, pulse peaks, pulse widths. discharge power and quantity appear in remarkably different ways. The transient onset voltage gap of two sequent discharge pulses are almost the same for argon discharge while are fluctuant for helium discharge. Under the same discharge conditions, the numbers of current pulses per half cycle for helium discharge are more than that for argon discharge. The current peaks of argon discharge are generally higher in amplitude than those of helium discharge, but are more narrow in width than those of helium. In each half cycle, the discharge quantity conducted in helium is more than in argon, while the power costed in argon discharge is more than in helium discharge. Therefore, an additional breakdown mechanism is proposed for argon plasma jet discharge to that for helium DBD in conclusion.