Ionization wave propagation and cathode sheath formation due to surface dielectric-barrier discharge sustained in pulsed mode

This work deals with the experimental study of a surface dielectric-barrier discharge, as a part of the ongoing interest in the control of plasma induced electro-fluid dynamic effects (e.g. plasma actuators). The discharge is generated using a plasma reactor consisting of a fused silica plate which is sandwiched between two printed circuit boards where the electrodes are developed. The reactor is driven by narrow high voltage square pulses of asymmetric rising (25 ns) and falling (2.5 μs) parts, while the discharge evolution is considered in a temporarily and spatially resolved manner over these pulses. That is, conventional electrical and optical emission analyzes are combined with high resolution optical emission spectroscopy and ns-resolved imaging, unveiling main characteristics of the discharge with a special focus on its propagation along the dielectric-barrier surface. The voltage rising part leads to cathode-directed ionization waves, which propagate with a speed up to 10⁵ m s⁻¹. The voltage falling part leads to cathode sheath formation on the driven electrode. The polarization of the dielectric barrier appears critical for the discharge dynamics.