Computer simulation of liquid metal ion source optics

A numerical calculation of the electric field and current density distribution for a liquid metal ion (LMI) source has been carried out. If a field evaporation mechanism for ion formation is assumed an elongated Taylor cone shape emitter is required to account for the observed total currents. Trajectory calculations including the effect of uniform space charge have been carried out as a function of total current and particle mass. The predicted emission characteristics compare favorably with experimental results for Ga, however the homogeneous space charge model is unable to account for all of the experimentally observed increase in beam divergence with increasing mass and current.