Advanced electrical current measurements of microdischarges: evidence of sub-critical pulses and ion currents in barrier discharge in air

Abstract

Electrical current measurements in corona or barrier microdischarges are a challenge as they require both high temporal resolution and a large dynamic range of the current probe used. In this article, we apply a simple self-assembled current probe and compare it to commercial ones. An analysis in the time and frequency domain is carried out. Moreover, an improved methodology is presented, enabling both temporal resolution in sub-nanosecond times and current sensitivity in the order of tens of microamperes. Combining this methodology with a high-tech oscilloscope and self-developed software, a unique statistical analysis of currents in volume barrier discharge driven in atmospheric-pressure air is made for over 80 consecutive periods of a 15 kHz applied voltage. We reveal the presence of repetitive sub-critical current pulses and conclude that these can be identified with the discharging of surface charge microdomains. Moreover, extremely low, long-lasting microsecond currents were detected which are caused by ion flow, and are analysed in detail. The statistical behaviour presented gives deeper insight into the discharge physics of these usually undetectable current signals.

The Equivalent Circuit Approach for the Electrical Diagnostics of Dielectric Barrier Discharges: The Classical Theory and Recent Developments

“…For example, if the discharge current waveform j R (t) is recorded for sinusoidal applied voltage, a sufficient time interval should be investigated with high sampling rate and resolution of analog-to-digital converter in a large dynamic range. This can be achieved with modern measurement technique (see [24]), but requires significant efforts.…”

“…For completeness, other approaches for electrical diagnostics of DBD should be mentioned: for example, statistical methods based on detailed analysis of the shapes of the current pulses measured in a DBD driven by sinusoidal voltage [24,26,27], modeling of the discharge processes [28][29][30], the simulation of the measured characteristics by defining the properties of lumped electrical elements of the equivalent circuit in XCOS/Scilab or the Simulink environment [31][32][33][34], or optical measurements of the electric field [35][36][37] and electron densities [38,39].…”

Robust current peak detection method for dielectric barrier discharges

“…electrons) start to move towards the electrodes and accumulate on the barrier, forming so-called surface charge. This charge motion causes a current peak that can be measured, see [15]. The electric field of surface charge compensates the applied voltage.…”

“…We have chosen case b) for the purpose of our study, primarily because we want our research to be closer to the application side of CDBD and, secondly, because the optimal case a) has been studied in many ways in history, e.g. [15,16]. In a case of our VDBD configuration, we have used standard VDBD configuration with both electrodes covered with an alumina (Al 2 O 3 ) dielectric barrier, see figure 14.…”

Plasma-assisted agriculture: history, presence, and prospects—a review

“…Although the definition of a microdischarge is not clearly specified, it mainly indicates the plasma at atmospheric pressure with dimensions of approximately 1 mm. The duration of a single micro-discharge is a range of 10-100 ns, and the transferred charge is of the order 0.1 nC for a 1 mm interelectrode gap [264][265][266][267]. The dielectrics may cover one or both electrodes, or they may be located in the space between them.…”