Combined and simultaneous electro-optical diagnostics for oscillatory plasma discharges
Résumé
The present work addresses the spatio-temporal character of dielectric-barrier discharge plasma arrays applied to generate virtual wall oscillations. Earlier investigations by the authors have uncovered an interplay of the re-occurring discharge onset and the resulting momentum transfer to the surrounding air. To bridge the gap between the evaluated electrical signals and the resulting flow manipulation in proximity of the individual discharge spot, optical diagnostics by means of intensified charge-coupled device (ICCD) imaging was conducted. As such, the light emission of the oscillatory plasma discharges was captured, allowing to characterize the discharge characteristics of the PA array for individual phase positions of the oscillation cycle. Through simultaneous acquisition of both current and voltage signals related to the captured image domain, the entire light emission is directly linked to the triggered micro discharges. As such, the impact of competing discharge filaments can be uncovered and, as a future scope, their influence on the resulting flow manipulation upon periodically changing forcing direction can be evaluated.