Interaction between electrospray using ionic liquid and simultaneous corona discharge under positive and negative polarity

One kind of ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate, is used to investigate the interaction between electrospray and corona discharge under positive and negative polarity. A high-speed camera, a digital camera, and an oscilloscope are applied to observe the shape of the meniscus and the jet, photograph the discharge plume, and observe the current waveform of discharge, respectively. The electrospray and discharge modes are studied under different flow rates and voltage conditions, and the experimental results show that there is only corona discharge with no jet at a low flow rate, while the intermittent jet or droplet emission is accompanied by corona discharge at a high flow rate, and no steady cone jet mode is obtained under all experimental conditions. The inevitability of corona discharge in the electrospray process of 1-ethyl-3-methylimidazolium tetrafluoroborate is analyzed from the viewpoint of electric field. Pulse discharge at low voltage depends on the oscillation of the meniscus. The frequency of pulse discharge can be changed indirectly by changing the voltage to control the oscillation of the meniscus. The influence of corona discharge and resultant space charge is not only on the electric field strength, but also on the shape, which is the reason why the liquid surface morphology is significantly different under positive and negative polarities.