The dependence of droplet charge distribution on frequency in liquid metal ion sources

Abstract

The charge distribution of microdroplets emitted from liquid metal ion sources (LMIS’s) has been investigated as a function of total beam current. For microdroplets with charges of more than 10 000 electronic units, the distribution changes rapidly with total beam current for currents of more than 60 μA. The charge distribution has also been examined when the extractor of the LMIS is driven with an external ac voltage. The total emission of highly charged microdroplets shows a resonance at ∼4 kHz. This resonant behavior may be related to surface wave instabilities that have been suggested as a primary mechanism of droplet formation.