Criterion for decrease of electric field at ionization point of liquid-metal ion sources

Abstract

Criterion for decrease of electric field at the ionization point of liquid-metalion sources has been derived. The argument is based on the equation of space-charge limited current with small charge approximation and the balance of electric field stress, with liquid flow and surface tension stress. The result was such that it is possible to decrease the electric field with an increase in the applied voltage, that is, the source current, under the condition of weaker dependence of current density on the electric field than that in the conventional low temperature field evaporation theory. The dependence of the ion current density on the electric field was calculated from the dependence of the angular current intensity on the electric field, assuming postionization theory. The result indicated that the dependence became almost proportional, which is surprisingly weak for field ion emission.