Distribution of energy release in ionization wave discharges propagating between two gas flows and along a surface

Summary form only given. The subject of the paper is visualization and dynamics of ionization wave discharges propagating along the interface of two media. The results of two experiments are presented: a single-electrode AC discharge sustained in a parallel flow of two different gases, and a nanosecond pulse ionization wave discharge propagating over a dielectric surface. In both cases, spatial and temporal distribution of energy coupled by the discharge is of particular interest. Dynamics of positive and negative polarity ionization waves in nanosecond pulse surface discharges in nitrogen and air is studied using nanosecond gate imaging and electric field measurements using a capacitive probe, over a wide range of pressures. The results suggest that the bulk of the energy is coupled behind the ionization wave front, at relatively modest values of the reduced electric field. The effect of specific localization of electrical discharge in immediate vicinity of two gases is discussed as well. In the most cases the AC and pulse discharges strives to the boundary between gases. The explanation of this fact includes the idea that the discharge localization is managed by the rule of minimal electrical field, required for the discharge maintenance, along the line of breakdown. This statement is illustrated by the well-adjusted schlieren photos of the streamers´ propagation. The next phase consists of the real selection of the discharge path among the multiple channels with non-zero conductivity. The experimental data are compared with theoretical and computational analyses. The primary applications of this work include lightning prediction / protection, mixing enhancement in non-premixed multi-component flows for high-speed combustion, and high-speed flow control.