DC Underwater Capillary Discharge With Symmetrical Hole: Diagnostics and Pumping Effect

Abstract

Capillary discharge investigated by this work was created in the reactor using positive half-cycle of AC high voltage up to 2 kV. Electric field was created between two electrodes which were separated by the dielectric ceramic barrier with a symmetrical cylindrical hole (diameter of 1 mm, length of 5 mm) in it. When voltage reached the value sufficient for liquid breakdown, the discharge appeared initially in bubbles of evaporated solution in the hole vicinity and spread further into the liquid volume. After the rise of discharge, two kinds of plasma channels (streamers) propagated towards electrodes from the pin-hole: longer positive streamers on the side with the cathode (analogically as in the positive corona discharge) and shorter negative streamers (like negative corona discharge). These streamer kinds differed especially in the energy dissipation originating from different electron velocities in plasma channels due to electron collisions with positive particles accelerating or decelerating electron avalanches and it gave rise of a significant pump effect. The weighing of flowing drops of aqueous solution was provided during the pump effect. Influence of parameters such as initial solution conductivity or input power on this effect as well as diagnostics by optical emission spectroscopy and electrical characteristics have been investigated.Capillary discharge investigated by this work was created in the reactor using positive half-cycle of AC high voltage up to 2 kV. Electric field was created between two electrodes which were separated by the dielectric ceramic barrier with a symmetrical cylindrical hole (diameter of 1 mm, length of 5 mm) in it. When voltage reached the value sufficient for liquid breakdown, the discharge appeared initially in bubbles of evaporated solution in the hole vicinity and spread further into the liquid volume. After the rise of discharge, two kinds of plasma channels (streamers) propagated towards electrodes from the pin-hole: longer positive streamers on the side with the cathode (analogically as in the positive corona discharge) and shorter negative streamers (like negative corona discharge). These streamer kinds differed especially in the energy dissipation originating from different electron velocities in plasma channels due to electron collisions with positive particles accelerating or decelerating electron avalanches and it gave rise of a significant pump effect. The weighing of flowing drops of aqueous solution was provided during the pump effect. Influence of parameters such as initial solution conductivity or input power on this effect as well as diagnostics by optical emission spectroscopy and electrical characteristics have been investigated.