Pulsed voltage driven electrospray

Abstract

This paper describes an electrospray driven by pulsed high voltages, compared to that driven by a direct current (DC) voltage. Using pulsed voltages is expected to deliver large amount of charges to the fluid surface, which allows us to control the behavior of the fluid. Pulsed voltage up to 30 kV was applied to a thin metal nozzle with a dripping ethanol from the tip. A time-resolved shadowgraph method was used to observe the behavior of the fluid in the electrospray. Our experiment shows the behavior of the fluid driven by pulsed voltages is clearly different from DC driven one. The dynamic formation of fluid jet occurs several hundred seconds after the pulse application because of its viscosity and inertial. Eventually the formed fluid jet split into several small jets, which was not seen in the DC driven electrospray. This indicates that the pulse voltage achieves high surface charge density exceeding the Rayleigh limit, resulting in the strong motive force for spraying.