The conditions of small disperse phase generation in the crucible type source of indium and of tin ions are investigated. The microdroplet emission cause by threshold means the instability of ion beam current. The charge particle dimension spectrum is continuous in the diapason up 20 to 400 but the frequency spectrum of oscillations is discrete the diapason up 2 to 30 MHz. The observed characteristics of liquid metal ion sources are interpreted in the frame of model of field steam ionization and of thermal liquid dispersion in the strong electrical field.