Eur. Phys. J. D (2014) 68: 224
https://doi.org/10.1140/epjd/e2014-50052-4

Regular Article

Influence of water conductivity on particular electrospray modes with dc corona discharge – optical visualization approach

¹ Division of Environmental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, 842 48 Bratislava, Slovakia
² Institute for Environmental Management Technology, AIST, Tsukuba, Japan

^a e-mail: branislav.pongrac@gmail.com

Received: 17 January 2014
Received in final form: 14 May 2014
Published online: 12 August 2014

Abstract

The effect of water conductivity on electrospraying of water was studied in combination with positive DC corona discharge generated in air. We used a point-to-plane geometry of electrodes with a hollow syringe needle anode opposite to the metal mesh cathode. We employed total average current measurements and high-speed camera fast time-resolved imaging. We visualized the formation of a water jet (filament) and investigated corona discharge behavior for various water conductivities. Depending on the conductivity, various jet properties were observed: pointy, prolonged, and fast spreading water filaments for lower conductivity; in contrast to rounder, broader, and shorter quickly disintegrating filaments for higher conductivity. The large acceleration values (4060 m/s² and 520 m/s² for 2 μS/cm and 400 μS/cm, respectively) indicate that the process is mainly governed by the electrostatic force. In addition, with increasing conductivity, the breakdown voltage for corona-to-spark transition was decreasing.