Dynamics of liquid in pulsed power-driven electrospray

Electrospray is a method to produce fine droplets from liquid materials and commercially used for painting, pesticide spraying, ionizing target materials in mass spectrometry, etc. The mechanism of electrospray driven by a direct current (DC) voltage has been understood well. The behavior of electrospray depends on the hydrodynamic and electrical properties such as viscosity, surface tension, permittivity and electrical conductivity. For this reason, only limited kinds of liquid materials are applicable to spray by the conventional DC-driven electrospray. On the other hand, there are several reports on the transient behavior of liquid under alternating current (AC) and pulsed voltages, which indicate that the behaviors of liquids and sprayed droplets depend on the frequency of applied voltages. They suggest that pulsed high voltage enables us to control the liquid dynamics, which show the possibility to spray liquid materials that are unable to be sprayed by the DC-driven electrospray. In this paper, we discuss the dynamics of liquid droplets driven by pulsed voltages.