Anomalous conical menisci under an ac field-departure from the dc Taylor cone

Observation of steady conical menisci with longitudinal growth is reported for electrospraying under high frequency alternating current (ac) electric fields. The authors report conical shapes that are analogous to the well-known direct-current (dc) cone-jet mode in the occurrence of conical menisci, but have some very distinctively ac features. The ac cones show a unique longitudinal growth that result in very high aspect ratio cones. The cone half angle for ethanol is approximately 9° for the ac case as compared to 47° for the dc case. These dissimilarities point to different mechanisms for dc and ac sprayings.