Temporal evolution of a surface dielectric barrier discharge for different groups of plasma microdischarges

Abstract

We have experimentally investigated the properties of microdischarges originating in asymmetric surface dielectric barrier discharges fed by a high-voltage sinusoidal low-frequency drive. Devices exploiting such a configuration are currently proposed as plasma actuators, because they induce a directed airflow in the gas surrounding the surface. Light emission and electric current associated with individual microdischarges have been recorded with high temporal resolution. A statistical analysis of the dataset was performed to correlate microdischarge properties with the voltage phase and to spot peculiarities arising from the actual breakdown mechanism in such a configuration. In particular, we demonstrated the asymmetry between the two different semi-cycles of the discharge, which could affect plasma actuator efficiency. Differences arising in the multiplicity, amplitude, temporal duration as well as in the spatial pattern of the discharge emitting region also permitted identifying several different groups of microdischarges, presumably playing different roles in both the discharge dynamics and airflow induction.

Spatial and temporal evolution of microdischarges in Surface Dielectric Barrier Discharges for aeronautical applications plasmas

“…The output of the PMT was registered by the low impedance input (50 Ω) of a large bandwidth digital oscilloscope (Agilent MSO8104A, 4 channels, time base 0.25 ns). As already discussed in similar experiments, the light emitted from each microdischarge appears in the PMT output as a few nanosecond pulse [6]. A typical signal is reported in figure 2.…”

“…In order to reconstruct the temporal evolution of the discharges we have used a PMT by Hamamatsu (H10721-210, having a 0.57 ns rise time) chosen for its fast temporal response and high sensitivity. Its ultra bialkali photocathode radiant sensitivity extends in the 230-700 nm range and peaks at 400 nm, closely matching the air DBD spectra [6]. Gain was maintained constant during experiments at 2x10 6 by regulating the potentiometer in the PMT supply circuit.…”

“…Its ultra bialkali photocathode radiant sensitivity extends in the 230-700 nm range and peaks at 400 nm, closely matching the air DBD spectra [6]. Gain was maintained constant during experiments at 2x10 6 by regulating the potentiometer in the PMT supply circuit. The output of the PMT was registered by the low impedance input (50 Ω) of a large bandwidth digital oscilloscope (Agilent MSO8104A, 4 channels, time base 0.25 ns).…”

“…DBDs and so also SDBDs driven by high voltage oscillating signals applied to electrodes happen generally in short bursts of activity, concentrated in two separated portions of the wave period. They are composed of a pretty large number of individual events, carrying electrical currents in the air gap between the electrodes, a microdischarge [4], each triggered by the propagation of an ionization wave [5][6]. There are several tricky aspects, including the geometry of the electrodes and the charging of the dielectric material surface facing the discharge region.…”

“…Here we presents results concerning the properties of microdischarges obtained by time resolved optical diagnostics using a photomultiplier tube (PMT) [6]. In particular we have measured the direction and the velocity of propagation of the ionization wave during the different phases.…”