Temporal dynamics of microdischarges in a dielectric barrier plasma actuator

Summary form only given. The use atmospheric plasma sources for applications in the aerodynamical and aeromotive sector is relatively new¹. The research focused mainly on the aerodynamics performances and to a much lesser extent to the plasma state. Indeed diagnostics of atmospheric pressure plasmas are very demanding because of the short temporal and the small spatial scales involved in the plasma state and in the different discharge regimes. Moreover such plasmas are often made up of intermittent and higly localized structures like stremers or microdischarges. We will presents results concerning the temporal behavior of microdischarges in a surface dielectric barrier discharge operated in the streamer regime. We have used both fast electrical probes made of suitable Rogoski coils² to measure individual current of each microdischarge. and photomultipliers and fast cameras to image and collect the emission light from the plasma³. Experimental results concerning the characteristics of the discharge, the influence of the discharge operating parameters and some interesting features observed in the properties of such intermittent discharges are presented. In particular the current signal is composed of burst of activity, each composed of several current peak, a few tens of ns in duration, corresponding to single microdischarges. We have studied the dependance of the number and duration of the bursts as a function of the power supplied. This parameters turns out to be linearly correlated to the peak voltage that is applied to the exposed electrode. Burst number increases linearly with power, after breakdown threshold, up to the highest power level. Their correlation with the phase of the oscillating high voltage is presented too. Then we discuss the effect produced by changing the thickness of the dielectric panel as well as its composition comparing different materials, like Teflon, Kapton and Plexiglas.