Capture of charged aerosols by a repelling plate in a bipolar electrospray configuration

Resumo

The bipolar electrospray configuration consists of an electrically conducting liquid pumped at a constant flow rate through a needle maintained at a constant voltage with a collecting plate located perpendicular to the needle and kept at a different voltage. A proper choice of needle voltage and plate voltage allows extending the domain of liquid flow rates leading to the electrospray working in the stable cone-jet configuration. The cone-jet mode is achieved even when an adverse voltage drop is imposed between the needle and the plate (with the surroundings kept grounded). Then, the charged aerosols emitted by the electrospray encounter a repelling electrical field near the plate. But still under these circumstances, some charges are collected by diffusion on the plate. In this experimental work the ratio of charges arriving to the collector with respect to the charges emitted at the needle is measured as a function of the experimental controlling parameters (voltages and flow rate). This diffusion leakage of charged particles against a repelling mean field is compared with previous theoretical predictions.